Comments on: 3.3 — Increment/decrement operators, and side effects http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/ Tue, 07 Feb 2012 12:30:29 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: zingmars http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/comment-page-1/#comment-96113 zingmars Sat, 08 Oct 2011 12:38:08 +0000 http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/#comment-96113 printf for some reason seems to evaluate the i++ once it's done, so it's 3 (you incremented it before using it - ++i) * 3 * 4. the second case (n=) simply evaluates the i++, and since the other additions are done only after the statement is done, you get 3*3*3 the first case is the same as the second one, except it adds +2 gained from the increments (i++) before. printf for some reason seems to evaluate the i++ once it’s done, so it’s 3 (you incremented it before using it – ++i) * 3 * 4.
the second case (n=) simply evaluates the i++, and since the other additions are done only after the statement is done, you get 3*3*3
the first case is the same as the second one, except it adds +2 gained from the increments (i++) before.

]]> By: nagaraj http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/comment-page-1/#comment-96090 nagaraj Wed, 05 Oct 2011 08:47:05 +0000 http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/#comment-96090 Hi all int i=2; i=++i * i++ * i++; answer i am geeting is 29 n=++i*i++*i++; answer i am getting is 27 printf(“%d”,++i*i++*i++); answer i am getting is 36 for same expression getting different values..please sort this problem how complier is going evalute? please reply me… Hi all
int i=2;
i=++i * i++ * i++; answer i am geeting is 29
n=++i*i++*i++; answer i am getting is 27
printf(“%d”,++i*i++*i++); answer i am getting is 36
for same expression getting different values..please sort this problem

how complier is going evalute? please reply me…

]]> By: nagaraj http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/comment-page-1/#comment-96089 nagaraj Wed, 05 Oct 2011 08:26:16 +0000 http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/#comment-96089 Hi all int i=2; i=++i * i++ * i++; answer i am geeting is 29 n=++i+i++*i++; answer i am getting is 27 printf("%d",++i+i++*i++); answer i am getting is 36 how complier is going evalute? please reply me... Hi all
int i=2;
i=++i * i++ * i++; answer i am geeting is 29
n=++i+i++*i++; answer i am getting is 27
printf(“%d”,++i+i++*i++); answer i am getting is 36

how complier is going evalute? please reply me…

]]> By: zingmars http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/comment-page-1/#comment-95995 zingmars Sat, 10 Sep 2011 09:16:09 +0000 http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/#comment-95995 It really depends on what you wanted to achieve in the first place. It really depends on what you wanted to achieve in the first place.

]]> By: quynhntn http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/comment-page-1/#comment-95988 quynhntn Wed, 07 Sep 2011 04:14:38 +0000 http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/#comment-95988 Fix me if i'm wrong n sorry about my bad english. Don't apply increment\decrement twice to the same variable. it make somthing ambiguous in C++ U can use a temp variable. Ex: i=i++*i++*++i*++i; int i = 1; int a = i++; ( a= 1, i = 2) a = a * (i++); ( a=2, i = 3) a = a * (++i); ( i =4, a = 2*4=8, ) a = a * (++i); ( i = 5, a = 8*5=40 ) Fix me if i’m wrong n sorry about my bad english.
Don’t apply increment\decrement twice to the same variable.
it make somthing ambiguous in C++
U can use a temp variable.
Ex: i=i++*i++*++i*++i;
int i = 1;
int a = i++; ( a= 1, i = 2)
a = a * (i++); ( a=2, i = 3)
a = a * (++i); ( i =4, a = 2*4=8, )
a = a * (++i); ( i = 5, a = 8*5=40 )

]]> By: zingmars http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/comment-page-1/#comment-95553 zingmars Mon, 13 Jun 2011 19:52:39 +0000 http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/#comment-95553 Wait, where's the problem? Your post isn't really specifying a problem. Wait, where’s the problem? Your post isn’t really specifying a problem.

]]> By: saurabh verma http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/comment-page-1/#comment-95545 saurabh verma Thu, 09 Jun 2011 19:43:09 +0000 http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/#comment-95545 i am facing lots of problem pls sort it out i= - --i-i-- - --i; i= ++i*++i*i++*++i; i=++i*++i*i++; i=i++*i++*++i*++i; i=i++*++i*++i; i=++i*++i*++i; plz sort this problem i am using gcc compiler... plz reply soon i am facing lots of problem pls sort it out
i= – –i-i– – –i;
i= ++i*++i*i++*++i;
i=++i*++i*i++;
i=i++*i++*++i*++i;
i=i++*++i*++i;
i=++i*++i*++i;
plz sort this problem
i am using gcc compiler…
plz reply soon

]]> By: saurabh verma http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/comment-page-1/#comment-95544 saurabh verma Thu, 09 Jun 2011 19:32:54 +0000 http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/#comment-95544 boss actually whatever you have expalined i am getting that is for turbo c but still i am facing lots of problem pls sort it out i= - --i-i-- - --i; i= ++i*++i*i++*++i; i=++i*++i*i++; i=i++*i++*++i*++i; i=i++*++i*++i; i=++i*++i*++i; plz sort this problem i am using gcc compiler... plz reply soon boss actually whatever you have expalined i am getting that is for turbo c but still i am facing lots of problem pls sort it out
i= – –i-i– – –i;
i= ++i*++i*i++*++i;
i=++i*++i*i++;
i=i++*i++*++i*++i;
i=i++*++i*++i;
i=++i*++i*++i;
plz sort this problem
i am using gcc compiler…
plz reply soon

]]> By: zingmars http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/comment-page-1/#comment-95541 zingmars Thu, 09 Jun 2011 15:18:13 +0000 http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/#comment-95541 I suspect that your compiler is being weird, because mine (VC++) outputs 14 in both cases (which it should). I suspect that your compiler is being weird, because mine (VC++) outputs 14 in both cases (which it should).

]]> By: zingmars http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/comment-page-1/#comment-95540 zingmars Thu, 09 Jun 2011 15:14:02 +0000 http://www.learncpp.com/cpp-tutorial/33-incrementdecrement-operators-and-side-effects/#comment-95540 It's as technorat said. consider this expression - x = (a++) + (a++); now what happens is it takes the value of a, adds the value of a to it, and then does the incrementing (if a - 5, then x will be 10, and a will be 7 in the end). It's the same thing when having ++ in front. example x = (++a) + (++a); It takes a value, increments it, then it sees another ++ in the statement, so it increments 'a' again, and then it does the adding, meaning that if a was 5, then x will be 14, and a will be 7 in the end. Also - you don't really need the brackets in this case, as ++ has higher priority than the standard + sign (tho it helps the readability). It’s as technorat said.
consider this expression – x = (a++) + (a++);
now what happens is it takes the value of a, adds the value of a to it, and then does the incrementing (if a – 5, then x will be 10, and a will be 7 in the end).
It’s the same thing when having ++ in front.
example x = (++a) + (++a);
It takes a value, increments it, then it sees another ++ in the statement, so it increments ‘a’ again, and then it does the adding, meaning that if a was 5, then x will be 14, and a will be 7 in the end.
Also – you don’t really need the brackets in this case, as ++ has higher priority than the standard + sign (tho it helps the readability).

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