How do I printf() a uint16_t?

问题:

I need to use printf() to print a uint16_t. This SO answer (How to print uint32_t and uint16_t variables value?) says I need to use inttypes.h.

However, I'm working on an embedded system and inttypes.h is not available. How do I print a uint16_t when the format specifier for a uint16_t is not available?

回答1:

An obvious way is:

printf("%u\n", (unsigned int)x);

The unsigned int is guaranteed to be at least 16 bits, so this is not a lossy conversion.

回答2:

You should use the style of inttypes.h but define the symbols yourself. For example:

#define PRIu8 "hu"
#define PRId8 "hd"
#define PRIx8 "hx"
#define PRIu16 "hu"
#define PRId16 "hd"
#define PRIx16 "hx"
#define PRIu32 "u"
#define PRId32 "d"
#define PRIx32 "x"
#define PRIu64 "llu" // or possibly "lu"
#define PRId64 "lld" // or possibly "ld"
#define PRIx64 "llx" // or possibly "lx"

Figure them out for your machine and use them. Take a look at others in inttypes.h and figure which you will need.

This way, your code will be more portable. I've been doing embedded systems work since the late 70's. Trust me: portability is important.

回答3:

short int is the smallest at least 16 bits long so convert the value to unsigned short int and print it with %hu.