1) Write a program that reads two numbers from the user, adds them together, and then outputs the answer. The program should use two functions: A function named ReadNumber() should be used to get an integer from the user, and a function named “WriteAnswer” should be used to output the answer. You do not need to write a function to do the adding.
2) Modify the program you wrote in #1 so that the function to read a number from the user and the function to output the answer are in a separate file called “io.cpp”. Use a forward declaration to access them from your main() function, which should live in “main.cpp”.
3) Modify the program you wrote in #2 so that it uses a header file to access the functions instead of forward declarations. Make sure your header file uses header guards.
Quiz solutions
1) Show Solution
#include <iostream>
int ReadNumber()
{
using namespace std;
cout << "Enter a number: ";
int x;
cin >> x;
return x;
}
void WriteAnswer(int x)
{
using namespace std;
cout << "The answer is " << x << endl;
}
int main()
{
int x = ReadNumber();
int y = ReadNumber();
WriteAnswer(x+y);
return 0;
}
2) Show Solution
io.cpp:
#include <iostream>
int ReadNumber()
{
using namespace std;
cout << "Enter a number: ";
int x;
cin >> x;
return x;
}
void WriteAnswer(int x)
{
using namespace std;
cout << "The answer is " << x << endl;
}
main.cpp:
int ReadNumber();
void WriteAnswer(int x);
int main()
{
int x = ReadNumber();
int y = ReadNumber();
WriteAnswer(x+y);
return 0;
}
3) Show Solution
io.cpp:
#include <iostream>
int ReadNumber()
{
using namespace std;
cout << "Enter a number: ";
int x;
cin >> x;
return x;
}
void WriteAnswer(int x)
{
using namespace std;
cout << "The answer is " << x << endl;
}
io.h:
#ifndef IO_H
#define IO_H
int ReadNumber();
void WriteAnswer(int x);
#endif
main.cpp:
#include "io.h"
int main()
{
int x = ReadNumber();
int y = ReadNumber();
WriteAnswer(x+y);
return 0;
}
2.1 — Basic addressing and variable declaration
Index
1.10a — How to design your first programs
first of all thanks for this site, I really appreciate the step by step help.
My first thoughts when attempting the quiz was “how do i get WriteAnswer() to use the results from ReadNumber()…
Also I would have never thought that ReadNumber() could define only x and be used like this inside main.cpp
So i had to cheat to understand how to accomplish quiz 1.
quick question i got from the above responses. Is using
when using cin or cout ok?? I notice other have posted doing this.
Again thanks for the site, I am a total beginner but I can now see my goal of creating a task/timekeeper for work might actually be possible.
edit to the above poster i am jsut guessing but maybe your io.cpp
should be
but I am guessing
I believe when they are using “” it is typos, because my compiler complains when i try it.
hey guys i couldn’t create a project with two files it mark me an error how can i do that?
That void function is tricky. I worked around it by asking the user for two inputs with different variables and then add them. It works as well, but it wasn’t the assignment.
#include "stdafx.h" #include <iostream> int som(int x, int y) { return x+y; } int main() { using namespace std; cout << "Enter a number: "; int x; cin >> x; cout << "Enter another number: "; int y; cin >> y; cout << "That adds up to: " << som(x,y) << endl; return 0; }I see the benefit now! There’s just one function that deals with the user input, in stead of asking input for every variable.
If I add another variable to main, it will ask for a third input automatically.
int main() { int x = ReadNumber(); int y = ReadNumber(); int z = ReadNumber(); WriteAnswer(x+y+z); return 0; }Funny, everyone seemed to be stumped by the same thing I was, the fact that WriteAnswer only had one int but main had two. Before reading posts about this or continuing with the test, I went back to the section on functions and figured it out, but this was a very tricky question to put on the test, since your examples were all (a,b) in both “main” and the “add” and “multiply” functions. I think you should go back to that section and add a blurb about the relationship between main and external functions, because though it all makes sense once you figure it out, this leads to unnecessary head-scratching for us fledgling coders. You could write a pared-down version of your response in an earlier post:
“Hmmm. When we say “int x” or “int y”, we’re telling the program that we’re defining a new variable, and we’re telling the program what type the variable is and what it’s name is. When a new variable is declared inside of a function, that variable’s name is only meaningful within that function. As a result, it is perfectly permissible to reuse the same variable name within multiple functions. This does not imply any kind of linkage between these variables.
Within main(), we declare two variables: x and y. These variables only exist within main(). We need two variables here because we have to hold two inputs.
Within ReadNumber(), we also declare one variable named x. This x has no relationship to the x we declared within main(). In fact, ReadNumber() doesn’t even know that another variable with the same name exists within main(). This is a good thing because it means we don’t have to worry about naming collisions.
We do not declare a variable y within ReadNumber() because ReadNumber() only needs one variable to do it’s job. Once ReadNumber() is finished executing, it passes it’s value back to the caller (main()). Main() then assigns that value to one of the variables it declared.
It might help you understand conceptually if you rename the x variable inside of ReadNumber() to “z”, or some other name that is not reused by main().”
thanks man. good explanation.
Thank You Jason for your explaination…that really worked for me
hey, great site :)
im using visual c++ 2008
i keep getting this error:
1>—— Build started: Project: Firstquiz, Configuration: Debug Win32 ——
1>Compiling…
1>Firstquiz.cpp
1>Linking…
1>Firstquiz.obj : error LNK2019: unresolved external symbol “void __cdecl WriteAnswer(int)” (?WriteAnswer@@YAXH@Z) referenced in function _main
1>Firstquiz.obj : error LNK2019: unresolved external symbol “int __cdecl ReadNumber(void)” (?ReadNumber@@YAHXZ) referenced in function _main
1>C:\Users\luke\Documents\Visual Studio 2008\Projects\Firstquiz\Debug\Firstquiz.exe : fatal error LNK1120: 2 unresolved externals
1>Build log was saved at “file://c:\Users\luke\Documents\Visual Studio 2008\Projects\Firstquiz\Firstquiz\Debug\BuildLog.htm”
1>Firstquiz – 3 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
any ideas what i can do to fix it?
Is it possible to return two integers with one function?
If so, please demonstrate how. Thanks.
#include "stdafx.h" #include <iostream> int som(int x, int y) { return x+y; } int main() { using namespace std; cout << "Enter a number: "; int x; cin >> x; cout << "Enter another number: "; int y; cin >> y; cout << "That adds up to: " << som(x,y) << endl; return 0; }Using the void is tricky.
Kaonashi did just as I did and it worked quite well.
I noticed that Alex’s code doesnt read the second input but simply prints the answer (the sum) immediately you input the second variable.
They both work anyway!
Thanks Alex.
i can’t get the solution of this programme.
my main.cpp is
int ReadNumber();
void WriteAnswer(int x);
int main()
{
int x = ReadNumber();
int y = ReadNumber();
WriteAnswer(x+y);
return 0;
}
io.cpp is
#include “stdafx.h”
#include
int ReadNumber()
{
using namespace std;
cout <> x;
return x;
}
void WriteAnswer(int x)
{
using namespace std;
cout << "The answer is " << x <
error is
LINK : warning LNK4067: ambiguous entry point; selected ‘mainCRTStartup’
1>main.obj : error LNK2019: unresolved external symbol “void __cdecl WriteAnswer(int)” (?WriteAnswer@@YAXH@Z) referenced in function _main
1>main.obj : error LNK2019: unresolved external symbol “int __cdecl ReadNumber(void)” (?ReadNumber@@YAHXZ) referenced in function _main
1>C:UsersSanjayDocumentsVisual Studio 2008Projectsjyocpp programmingquiz1.11bDebugquiz1.11b.exe : fatal error LNK1120: 2 unresolved externals
1>Build log was saved at “file://c:UsersSanjayDocumentsVisual Studio 2008Projectsjyocpp programmingquiz1.11bquiz1.11bDebugBuildLog.htm”
1>quiz1.11b – 3 error(s), 1 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
i can’t correct this error.pls give some idea.
Your two prototypes are very messed up.
Your int ReadNumber() should look like:
int ReadNumber() { using namespace std; cout << "Input value please: " << endl; int x; cin >> x; return x; }And your void WriteAnswer(int x) should look like:
void WriteAnswer(int x) { using namespace std; cout << "Your answer is: " << x << endl; }i can’t get the solution of this programme.
my main.cpp is
int ReadNumber();
void WriteAnswer(int x);
int main()
{
int x = ReadNumber();
int y = ReadNumber();
WriteAnswer(x+y);
return 0;
}
io.cpp is
#include “stdafx.h”
#include
int ReadNumber()
{
using namespace std;
cout <> x;
return x;
}
void WriteAnswer(int x)
{
using namespace std;
cout << "The answer is " << x <LINK : warning LNK4067: ambiguous entry point; selected ‘mainCRTStartup’
1>main.obj : error LNK2019: unresolved external symbol “void __cdecl WriteAnswer(int)” (?WriteAnswer@@YAXH@Z) referenced in function _main
1>main.obj : error LNK2019: unresolved external symbol “int __cdecl ReadNumber(void)” (?ReadNumber@@YAHXZ) referenced in function _main
1>C:\Users\Sanjay\Documents\Visual Studio 2008\Projects\jyo\cpp programming\quiz1.11b\Debug\quiz1.11b.exe : fatal error LNK1120: 2 unresolved externals
1>Build log was saved at “file://c:\Users\Sanjay\Documents\Visual Studio 2008\Projects\jyo\cpp programming\quiz1.11b\quiz1.11b\Debug\BuildLog.htm”
1>quiz1.11b – 3 error(s), 1 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
i can’t correct this error.pls give some idea.
Look up ^^
At first, Thanks a lot for your wonderful and descriptive tutorial. It’s really amazing!
I use Turbo c++ 4.5 (windows version) for writing c++ program(My computer is so old and I can’t install visual studio on it). I write 3 piece of code as you said:
(1)main.cpp
#include "IO1.h" int main() { int x = ReadNumber(); int y = ReadNumber(); WriteAnswer(x+y); return 0; }(2)IO1.cpp
#include <iostream.h> int ReadNumber() { cout << "Enter a number: "; int x; cin >> x; return x; } void WriteAnswer(int x) { cout << "The answer is " << x << endl; }(3)IO1.h
I saved IO1.h in INCLUDE directory. but I don’t know what should else I do?!! There’s no place in tc4.5 like visual studio to add another file to my previous project or I don’t know where it’s. When I compile my main there are these errors :
Linker error : Undefined symbol WriteAnswer(int) in a module MAIN.CPP
Linker error : Undefined symbol ReadNumbera(int) in a module MAIN.CPP
No real problem here, you only forgot to add your namespaces in, well… everywhere.
Thanks for your reply. but the problem is that I can’t use “using namespace std”. If I put this phrase in my program I will get an error. I can compile and run my program without this phrase easily!!
The reason why you cant use namespaces is cause your using the iostream.h header, instead try using the iostream header (iostream.h and iostream are two different header files), than use namespaces, Hope this helps.
hmm i couldnt do question 1 on my own, so i copied out your code in the answer, but it just flashes and goes away, i tryed putting in
system (“pause”); and stuff, but it still aint working for some reason :/
using DevC++
thanks
try this:
getch();
:D
What runtime is that in?
Take away the “return 0;” in int main().
i am really grateful for this wonderful tutorial, your response to people’s question has answered mine.
Kiitos!! it means thank you in finnish
Wow, I did it. Thank you so much! The only problem being the site loads up very slow sometimes :[ I understand this is because of how many people are there, but it’s lame :[[
Can some body please help me.
Why does this generate an answer of 2 ever single time (no matter what x,y are)
#include
using namespace std;
int readNumber(int x, int y, int z)
{ cout <> x;
cout <> y;
return z=x+y;
}
void writeAnswer(int z)
{cout << "The answer is : " << z;}
int main()
{
int x,y,z;
readNumber(x,y,z);
writeAnswer(z);
system ("pause");
return 0;
}
I’m pretty clueless mate, but, shouldn’t
cout x;
cout y;
be
cin >> x;
cin >> y;
?
#include
using namespace std;
int readNumber(int x, int y, int z)
{ cout <> x;
cout <> y;
return z=x+y;
}
void writeAnswer(int z)
{cout << "The answer is : " << z;}
int main()
{
int x,y,z;
readNumber(x,y,z);
writeAnswer(z);
system ("pause");
return 0;
}
hello i wrote this progam
// io.cpp : Defines the entry point for the console application.
//
#include “stdafx.h”
#include
int ReadNumber()
{
using namespace std;
cout <> x;
return x;
}
void WriteAnswer(int x)
{
using namespace std;
cout << "The answer is " << x << endl;
}
and
// main2.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include
int ReadNumber();
void WriteAnswer(int x);
int main()
{
int x = ReadNumber();
int y = ReadNumber();
WriteAnswer(x+y);
return 0;
}
bt they r showin an error to this
like
1>—— Build started: Project: main2, Configuration: Debug Win32 ——
1>Linking…
1>main2.obj : error LNK2019: unresolved external symbol “void __cdecl WriteAnswer(int)” (?WriteAnswer@@YAXH@Z) referenced in function _main
1>main2.obj : error LNK2019: unresolved external symbol “int __cdecl ReadNumber(void)” (?ReadNumber@@YAHXZ) referenced in function _main
1>C:\Documents and Settings\HCL\My Documents\Visual Studio 2008\Projects\main2\Debug\main2.exe : fatal error LNK1120: 2 unresolved externals
1>Build log was saved at “file://c:\Documents and Settings\HCL\My Documents\Visual Studio 2008\Projects\main2\main2\Debug\BuildLog.htm”
1>main2 – 3 error(s), 0 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
pl wt s da problem
Alright Alex?
Loving the guide so far, it’s really well written and very helpful and i’ve had no problems up untill now.
But i was wondering, is it bad that i couldn’t figure this out?
I spent nearly two hours trying different things, but didn’t really get close to figuring it out, the only thing i managed to do was build a program that did the same thing but didn’t obide by your rules.
But my question is, should i really know how to do this problem by now? Is it a bad thing that after me seemingly thinking i learned everything so far in your tutorial, i couldn’t put the pieces together and figure out this problem? :)
Thank you alex sir…. Excellent tutorials….
MSVCRTD.lib(crtexe.obj) : error LNK2019: unresolved external symbol _main referenced in function ___tmainCRTStartup
why do i get this error whenever i type the code out myself, i have compared every little tidbit of code and i still get this… any help?
Also when doing problem #3 when trying to write the header guards it shows up that the directive is missing for #ifndef and it doesnt even recognize #endif
i dunno what im doing wrong :(
great and xplicit presentation, wonderful lessons, superb back/follow up quiz. this is just it.
THE BEST FREEEEEEEEE!!!! C++ TUTORIAL
THANKS ALEX, U’RE GREAT.
I’m having a problem, and I’m not sure what exactly is going on. I need to have #include “io.cpp” in my io.h file for my program to work. I’m not sure if that’s the way it should be, or if I made a mistake and that #include “io.cpp” is just shunting around the mistake. Here’s my code:
main.cpp
#include <iostream> #include "io.h" // add takes two integers as parameters, and returns the result of their sum // add does not care what the exact values of x and y are int main() { using namespace std; int first = ReadNumber(); int second = ReadNumber(); WriteAnswer(second + first); cin.clear(); cin.ignore(255, '\n'); cin.get(); return 0; }io.cpp
#include <iostream> int ReadNumber() { using namespace std; cout << "What's the number you want to add?"; int number; cin >> number; return number; } void WriteAnswer(int number) { using namespace std; cout << "When added, the answer is: " << number << endl; }and lastly, my header file, io.h:
I know this site went up a while ago, but hopefully someone still reads the comments. Thanks you!
i can’t compile your program even though i pasted it. in both #2 and #3 compiler complains that functions are not defined.
Solution 3 won’t work for me unless I put
#include “stdafx.h”
#include
before putting
#include “io.h”
how come?
I’m confused, in the main function where you declare
int x = ReadNumber(); int y = ReadNumber();Is that ReadNumber() a function call or a value? If it’s a value (which I assume) then I don’t see the part where there’s a call to ReadNumber() from main(), so it must be a call? But I didn’t know calls could be used as a variable value though? Has this been covered in a previous section or have I missed it?
It’s a function call. He initalizes x (and y), and assigns the value outputted by ReadNumber(); function (which is the number you entered using cin.
HI, So can someone give me other quizzes too because sucked at these.
So i copied the exact awnser given for quiz one into MS visual C++ 2010 and tried to run it and could not for the life of me get it to work. is there some obvious addition that had been left out of the awnser, due to perhaps how seemingly obvious its presence would be or is there some mistack i have not managed to find? and i did add in ” #include “stdafx.h” ” as my first line for obvious reasons.
why does this ask for x and y twice.
Please help.
#include “stdafx.h”
#include
int add(int x,int y)
{
return (x + y);
}
int ReadNumber()
{
using namespace std;
cout << "please enter an x value" <> x;
cout << "please enter a y value" <> y;
return x, y;
}
void WriteNumber(int x,int y);
int main()
{
int x = ReadNumber();
int y = ReadNumber();
WriteNumber(x, y);
return 0;
}
void WriteNumber(int x,int y)
{
using namespace std;
cout << "your answer is " << add(x, y) << endl;
cin.clear();
cin.ignore(255, '\n');
cin.get();
}
Hi, I just wish to know why we put “using namespace std;” in every function which we use “cout…endl”. Because I wrote it top of the page rigt after “#include ” and it works. Isn’t this more sensible because we do not need to write it for every “cout…end” and isn’t this faster for compiler. I am not sure. I think this is called like global which affect every function.
Please, alex or anyone and thanks.
I was thinking the same thing. Seems a lot simpler to just put it at the top and make it “global” as you said.
Also what is wrong with just writing:
#include “stdafx.h”
#include
using namespace std ;
int main ()
{
int x;
int y;
cout <> x >> y ;
cout << "The answer is: " << x + y << endl;
return 0 ;
}
Simpler is better imo
*oops copied wrong
#include “stdafx.h”
#include
using namespace std ;
int main ()
{
int x;
int y;
cout <> x >> y ;
cout << "The answer is: " << x + y << endl;
return 0 ;
}
idk why but when i submit comment it switches the code all around :/ so i guess nvm
chachoblow
to write it like that is to go around what alex is trying to convey, how to use the linker for header files and declarations. it is good to see you are in the mind set of thinking ahead and outside of the box this early in the tutorial. Bravo sir!!
This is strange. I did the code and it seemed like it should have worked, but for some reason it wouldn’t recognize #ifndef and #endef. I kept getting this error:
fatal error C1021: invalid preprocessor command ‘endef’
So, I checked the solution to see what i did wrong, and it looked pretty similar to what I did. I checked it against the code and copied and pasted their solution into my code, except for on the io.h file. It still didn’t work, even though my io.h file was exactly the same as theirs. I then copied and pasted theirs in, and it worked. There was literally no change from before i pasted it in to after, except that after, it somehow worked. I do not understand D:
I started again from a blank slate, and I see what the problem was. I’m not sure how i didnt notice it, but I wrote #endef instead of #endif.
hey guys!
i’m in kind of a fix and was wondering if you could help me out. For the first question i made the code accordingly and fixed all the debug errors, but this error won’t go away! Here’s my code. Please post back soon…
#include
#include
int ReadNumber()
{
using namespace std;
cout << "To find the addition of two numbers please think of two numbers." << endl <<"Now enter the first number" <> x
cout << endl;
cout << "Good, now enter the second number" <> y ;
cout << endl
return x,y;
}
int WriteNumber(int x, int y)
{
using namespace std;
cout << "The sum of your two numbers is " << x+y << endl;
return 0;
}
int main()
{
using namespace std;
ReadNumber();
WriteNumber();
return 0;
}
ERRORS
in function 'int ReadNumber' o few arguments to function 'int WriteNumber (int, int)'
error: at this point in the file
error :t
2x #include? what exactly did you include?
ReadNumber() does not have any numbers defined (should be ReadNumber(int x, int y)).
Also you need to use Cin >> x (or y) to take input. Even if your compiler supports such monstrosities, you’re not supposed to do it like that.
Also you can simply add << endl the end of the cout.
Missing semicolons.
You should've used void WriteNumber(int x, int y), because it's not supposed to return any value.
You should re-read all the tutorials before, because it will require a lot of rewriting to get it to working state.
Ah, never mind. I didn’t notice that this comment box somehow destroys your code formatting for some reason. Either way, I would guess that the problem came from the fact that WriteNumber wasn’t void, and that you didn’t do the whole WriteNumber(int x, int y) thing.
Woosh! Well that wasn’t easy.
I did the first one a bit differentially than Alex did, but then I noticed that my version was going to be harder to implement in the 2nd one, so I had to rewrite my code a bit
(what I did was:
#include
int ReadNumber(int x); //I knew that I’ll need those later
void WriteAnswer(int x, int y)
int main()
{
including namespace std;
int x = 0;
ReadNumber(x);
int y = 0;
ReadNumber(y);
WriteAnswer(x, y);
int something; //VS10 closes the program as soon as the instructions end, so I put this in to see the output
cin >> int;
return 0;
}
int ReadNumber(int x)
{
using namespace std;
cout <> x;
return x;
}
void WriteAnswer(int x, int y)
{
using namespace std;
cout << "The answer is " << x + y << endl;
}
(Note that there might be some mistakes, because I did this on fly in the comment box, because I deleted my old code :D)
)
And for the 2nd one I had a silly typo, but did guess it myself after all (took me like 20 minutes for this whole thing. Most time was spent figuring out the cryptic compiler messages. I guess I should've planned it out huh?).
3rd one was ez 1 minute job.
Anyway, why Header Guard? Why not #pragma once? I mean, it's unlikely that any modern compiler will fail to recognize it or anything…
Could you please give me a hint. I have mostly the same code as yours. When I run it, I can enter two numbers, but then the command line just closes not showing any result.
#include “stdafx.h”
#include
int ReadNumber()
{
using namespace std;
cout <> x;
return x;
}
/*int CalculateResult(int x, int y)
{
return x + y;
}*/
void WriteAnswer(int Result)
{
using namespace std;
cout << "Result: "<< Result << endl;
}
int main()
{
int x=ReadNumber();
int y=ReadNumber();
//int Result=CalculateResult(x, y);
WriteAnswer(x+y);
//return 0;
}
It’s because once the result is printed on the screen, the program receives the command to return 0 to OS, closing the program. To prevent that there are multiple options, however the best one in this case would be adding cin >> x; (or anything you’ve declared before, if you’re not feeling like declaring something new) before the return 0;
Thanks a lot, zingmars!
I’m hoping someone can help. I’m currently on #2 and have the EXACT code in the solution, but getting the following error message:
Warning 1 warning C4627: ‘#include ‘: skipped when looking for precompiled header use c:\Users\Owner\documents\visual studio 2010\Projects\ConsoleAddQuiz\ConsoleAddQuiz\io.cpp 1 1 ConsoleAddQuiz
Error 2 error C1010: unexpected end of file while looking for precompiled header. Did you forget to add ‘#include “StdAfx.h”‘ to your source? c:\Users\Owner\documents\visual studio 2010\Projects\ConsoleAddQuiz\ConsoleAddQuiz\io.cpp 16 1 ConsoleAddQuiz
Any ideas what could be causing this? I’m using Microsoft Visual Studio 2010.
Thanks in advance!
You probably had “Use Pre-compiled header” setting on, and you erased the code that MS IDE had for you when you opened that project.
Try creating a new project, but this time disable the pre-compiled header option, and try again.
That was it! Thanks so much for the help. :)
Hi there,
First of all I would like to say thank for the useful website, next I have a question I was wondering is it better to declare the using namespace std within the header file so you only ever call it once? As shown below:
// — Define preprocesses — //
#ifndef IO_H // — Header guard — //
#include
using namespace std;
int ReadNumber();
void WriteNumber(int x);
#endif
Kind Regards
FlippA
Nah, better declare it in each file, because there might be files that don’t need to use that namespace, and it might make your compiler scream in pain.
Ok, so i am a noob at C++, and need some help. For the first quiz question i tried putting this
#include
main()
{
using namespace std; //So cin and Cout can be used
cout <> x; //Reads number from console and stores it in x
cout <> y; //Reads number from console and stores it in y
cout << "Your number is: " << cout << x + y; //Displays final number in console
return 0;
}
But, once I compile it, it ends up giving some random "number" which is not really a number because it has x and c in it, which obviously is not what i was expecting. Some help would really be appreciated.
you don’t need the cout before the x+y part (or seperate that part from the “Your number is: ” using semi-colon.)
Hey! Great Tutorial man!
I was attempting the second problem but i cannot figure out this error.
the code and the error are:
io.cpp
#include
using namespace std;
int a=0,b=0;
int Readnumber()
{
cout<>a;
cout<>b;
return a+b;
}
void Writeanswer()
{
cout<<"the answer is "<<Readnumber();
}
main.cpp
int Readnumber();
void Writeanswer();
int main()
{
Writeanswer(); // error HERE!
return 0;
}
error obj\Debug\main.o||In function `main':|
C:\Program Files\CodeBlocks\Quiz1.2\main.cpp|9|undefined reference to `Writeanswer()'|
||=== Build finished: 1 errors, 0 warnings ===|
Please help me out. Seems trivial i know. :/
Ok! I got it. So I didnot select Debug and release while creating the new file (in code blocks). That was the problem.
Can Anyone tell me why that is important??
Refer to Code::Blocks documentation and/or forums for that, as this is not related to C++ language itself.
i believe the problem lies at void WriteAnswer()
as far as my understanding goes you need to declare a variable, which can hold return value from ReadNumbers() function.
segment of my code was as follows:
void WriteAnswer()
int z = ReadNumbers()
cout << "Sum of both numbers is " << z << endl;
and my main was just like yours.
Someone please correct me if i am wrong.
I am having a serious problem with getting problems 2 and 3 to work. I’m even copying and pasting exactly into files and I can’t get it to run properly.
For problem number two I am getting the errors:
Quiz1.obj : error LNK2005: “int __cdecl ReadNumber(void)” (?ReadNumber@@YAHXZ) already defined in io.obj
1>Quiz1.obj : error LNK2005: “void __cdecl WriteAnswer(int)” (?WriteAnswer@@YAXH@Z) already defined in io.obj
Can anyone help me out with this?
Thank you
Make a new project, or use a different compiler, because it seems that you have ReadNumber and WriteAnswer defined somewhere else.
hello everyone i am having a problem with the third exercise, well the problem is with the header blocker i am using code blocks as ide in Ubuntu here is the problem.
io.h
#unfdef IO_H
#define IO_H
int Readnumber();
void Writeanswer(int x);
#endif
this the error i get when i compile it
error:invalid preprocessing directive #infdef
error:#endif without #if
i dont put the other parts because i know they are right, but if you want i can post it.
Hey Kamakasy, I think you have a typo. Change “unfdef” to “ifndef”.
#include “stdafx.h”
#include
int Number1;
int Number2;
int Operation;
int Result;
int Getnumbers()
{
using namespace std;
cout <> Number1;
cout <> Number2;
return (0);
}
int Getoperation()
{
using namespace std;
cout <> Operation;
return (Operation);
}
int Calculate(int, char, int)
{
if (Operation = ‘+’)
return Number1+Number2;
if (Operation = ‘-’)
return Number1-Number2;
if (Operation = ‘*’)
return Number1*Number2;
if (Operation = ‘/’)
return Number1/Number2;
return (0);
}
void Printresult(int)
{
using namespace std;
cout << "Your Result Is " << Result << endl;
}
int main()
{
Getnumbers();
Getoperation();
Result = Calculate(Number1, Operation, Number2);
Printresult(Result);
}
this is my calculator code but it will only add the two numbers instead of any thing else. Help im a N00B.
#include “stdafx.h”
#include
int Number1;
int Number2;
int Operation;
int Result;
int Getnumbers()
{
using namespace std;
cout <> Number1;
cout <> Number2;
return (0);
}
int Getoperation()
{
using namespace std;
cout <> Operation;
return (Operation);
}
int Calculate(int, char, int)
{
if (Operation = ‘+’)
return Number1+Number2;
if (Operation = ‘-’)
return Number1-Number2;
if (Operation = ‘*’)
return Number1*Number2;
if (Operation = ‘/’)
return Number1/Number2;
return (0);
}
void Printresult(int)
{
using namespace std;
cout << "Your Result Is " << Result << endl;
}
int main()
{
Getnumbers();
Getoperation();
Result = Calculate(Number1, Operation, Number2);
Printresult(Result);
}
sorry this is the real code my computer failed
Operation needs to be a char, not an int.
When comparing things, use two equals sign.
And… this is my trial… :D
File : main.cpp
#include
#include “nUser_input.h”
#include “nSum.h”
using namespace std;
int main()
{
int nResult;
int y;
nResult = WriteAnswer(y);
cout << "Sums of the two number: " << nResult << endl;
return 0;
}
File : nSum.h
#ifndef NSUM_H_INCLUDED
#define NSUM_H_INCLUDED
int WriteAnswer(int x)
{
int nInput_1 = Read_Number();
int nInput_2 = Read_Number();
return nInput_1 + nInput_2;
}
#endif // NSUM_H_INCLUDED
File : nUser_input.h
#ifndef NUSER_INPUT_H_INCLUDED
#define NUSER_INPUT_H_INCLUDED
#include
using namespace std;
int Read_Number()
{
cout <> nInput;
return nInput;
}
#endif // NUSER_INPUT_H_INCLUDED
really wonder what to do when the instruction tell can’t use function to sum up the number input, so i just use return x + y ‘trick’…. xD
haha.. grabeh wla akong idea panu ko siya gagawin..
XD
more practice needed.. :D
First of all I would like to thank you a lot for providing such a holistic and easy to understand material on C++. Its really fun learning with you. Thank you again.
After having gone through Quiz 1, I have following queries:
1. int WriteAnswer() can be used instead of void WriteAnswer(), code works perfectly alright with this. Whats really the difference between both.
2. Will there be detailed section on different/preferential ways on piping input/output results between/among function?
3. Following is my code on Q1 Quiz 1 (I was only able to get my code running only after going through the solution). I would appreciate few comments.
#include //Quiz 1 my solution after consulting answer from learncpp(dot)com
int ReadNumber()
{
using namespace std;
int x;
int y;
cout <> x;
cout <> y;
return x+y;
}
void WriteAnswer()
{
using namespace std;
int z = ReadNumber();
cout << "Sum of Both Numbers is " << z << endl;
}
int main()
{
WriteAnswer();
return 0;
}
Another thing, you said in some section that using cout in some function with void return type would create a compiler error, however we see void WriteAnswer() working fine, how?