stdint.h can't be reliably be premade. A compiler is completely free to, say, define sizeof(unsigned int) to anything as long as it can represent at least 65535

stdint.h can't be reliably be premade. A compiler is completely free to, say, define sizeof(unsigned int) to anything as long as it can represent at least 65535. stdint.h has to work with the C base types, so it does have to be customized for a particular compiler.