Question

I’m reading a C code that do

char * buf = malloc(sizeof (char *) * 16)

instead of

char buf[sizeof (char *) * 16]

what’s the difference? well, I think the first expression unnecessary, if realloc() is not called, or am I wrong thinking?

Answer 1

char buf[sizeof(char*)*16] is an array allocated automatically, which is generally the stack. It is valid as long as buf is in scope, and there is sufficient stack space.

malloc allocates memory from some heap. It is valid until this memory is free()ed. Generally, there is much more heap available.