Trouble with free()

Question

Could someone tell me what, if anything, is wrong with this bit of code regarding the usage of free (or anything working up to it)? This code works w/no errors in Xcode, but in Visual C++, I get a heap corruption error when free() is called. Another open source IDE doesn't give any error on it either. Is Microsoft confused, or are they being more vigilant about memory usage and I'm doing something wrong?
int* pi;
int* pi2;
pi = pi2 = (int*) malloc(10);
for (int i = 0; i < 10; i++)
*pi = i;
printf("%d
", *pi++);
pi = pi2;
printf("%d
", *pi);
free(pi);
getchar(); // this is just here to leave the command line window open because it closes automatically once execution finishes
return 0;

Answer 1

Microsoft is well known for flaky software and "liberal" interpretation of things like language standards and such. However, the VC++ compiler itself is one of the best there is. The fact that GCC doesn't care about this code is GCC's problem. GCC is free and ubiquitous, but not especially good.
The problem is that you are allocating 10 bytes and then attempting to store 10 int's into that memory. An integer can take anywhere from 2 to 8 bytes, depending on your machine, OS, and compiler settings. It is defined to be undefined. What you want to do is:
(int *)malloc(10 * sizeof(int));