i have found the following expression in C
According to the book it is undefined behavior but little confused why it is so. My interpretation would be something like thisCode:a[i] = i++;
a. the expression on the right will be evaluated first that is i,
b. then it would be assigned to a[i],
c. then i will be incremented.
What is that i am missing here? Why is it not correct way of writing?
When you use post-incrementation on a variable that you use in the same expression multiple times, you invoke "undefined" behavior. Meaning that there's no certain way how this will be resolved. One compiler may decide to do:
while another compiler may do:Code:a[i] = i; ++i;
so on and so forth...Code:temp = i++ a[i] = temp
EDIT:
The reason the post-increment/decrement operators have this behavior is because of their undefined nature, the standard doesn't enforce whether the variable should change right there or after the expression is finished, so the compiler manufacturer picks what suites them best.
Last edited by GReaper; 04-10-2017 at 06:50 AM.
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In C, operations are allowed to be performed in any order except where specified by sequence points.
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