Unlike Purify and Valgrind, Insure++ inserts its instrumentation at the source code level, which allows it to detect errors that the other tools miss. In particular, Insure++ can detect buffer overflows in automatic arrays, and overflows which involve pointers that accidentally "jump" from one valid memory region to another, as in the following example:
int main()
{
char *p = malloc(1024); /* first dynamically-allocated block */
char *q = malloc(1024); /* second block */
p += 1200; /* At this point, "p" is likely to point into the second block.
However, false assumptions about the real behaviour lead to mistakes. */
*p = 'a'; /* invalid write (past the end of the first block) */
return 0;
}
Also the source level instrumentation allows it to not only identify that a leak occurred, but where it occurred. Some tools merely provide information about where the memory was allocated, Insure++ also gives a stack trace for when/where the actual leak occurred.