iostream vs. stdio

so, I've got EXPERT PROGRAMMERS telling me to use printf instead of cout in c++, ok but why? what is the difference (in b4 stream)

>>64
Look into <stdint.h> and <inttypes.h>
They've added stuff like uint64_t for example, and to print it using printf() you write

uint64_t n = UINT64_MAX;
printf("%"PRIu64"\n", n);