Comments on: 6.1 — Arrays (Part I)

By: Sinni

Sinni — Sat, 19 Jul 2008 15:20:56 +0000

int anTestScores[30]; // allocate 30 integers || anArray[3]; // allocate 3 integers

If it starts counting at 0, shouldn’t these instead read anTestScores[29] and anArray[2] ?

By: Learn C++ - » 5.8 — Break and continue

Learn C++ - » 5.8 — Break and continue — Tue, 29 Apr 2008 04:49:37 +0000

[...] 2007 Prev/Next Posts « 5.7 — For statements | Home | 6.1 — Arrays (Part I) » Tuesday, June 26th, 2007 at 4:22 [...]

By: Alex

Alex — Sat, 05 Apr 2008 04:02:11 +0000

I’m not sure I understand your question. What do you mean by an unknown number of elements?

It sounds to me like you’re talking about arrays where the size isn’t known in advance — this is handled via dynamic allocation, and is covered in lesson 6.9.

By: greensteepe

greensteepe — Fri, 04 Apr 2008 19:58:15 +0000

thanks Alex!
Would you tell me about array with unknown number elements?
thank you so much!

By: programmer

programmer — Sun, 09 Mar 2008 04:37:24 +0000

thanks Alex

but I still get some confuse .. could you please give an example like a complete program about what we could do with array ..

thanks

By: Allen01

Allen01 — Thu, 21 Feb 2008 19:03:30 +0000

Thanks, it makes more sense now.

By: Alex

Alex — Thu, 21 Feb 2008 18:49:53 +0000

nIndex is the assigned index value. We set the value of nIndex on line 2 of your example. The element value is what comes after the assignment on the third line.

To be as clear as possible: array indices must be integers. You can use either a literal index:

anArray[3] = 7;

or a variable index:

int nIndex = 3;
anArray[nIndex] = 7;

nIndex doesn’t have to be a constant integer.

Both of the above examples do the exact same thing: assign the value of 7 to array element 3. When the statement anArray[nIndex] = 7 is evaluated, the array index part takes precedence and is evaluated first. nIndex is evaluated to produce the value 3, and then anArray[3] = 7 assigns the value 7 to array element 3.

The index itself is just an integer — thus, no need for []. You only need the [] when you’re accessing the array itself.

By: Allen01

Allen01 — Thu, 21 Feb 2008 16:40:46 +0000

Alex, not sure what is meant in this example, where array elements may be accessed by a non-constant integer variable; is “nIndex” the assigned index value, or is it an element value? I understand the first line and the last line seems to indicate that the value of 7 is being put into element nIndex. If so, should nIndex on line 2 be in [ ]?

int anArray[5];
int nIndex = 3;
anArray[nIndex] = 7;

By: Learn C++ - » 10.4 -- Container classes

Learn C++ - » 10.4 -- Container classes — Sat, 15 Dec 2007 00:54:21 +0000

[...] and restrictions in their use. By far the most commonly used container in programming is the array, which you have already seen many examples of. Although C++ has built-in array functionality, [...]