> You cannot make them work with printf("%d", x) directly (it compiles fine and then you run into problems), etc. To be fair that's also true for standard intN

> You cannot make them work with printf("%d", x) directly (it compiles fine and then you run into problems), etc. To be fair that's also true for standard intN_t or uintN_t types. "%d" expects an int argument, and while several of the intN_t types may be converted to int by the default argument type promotion rules, that isn't guaranteed. For example, while plain "%d" works for int64_t on ILP64 platforms with 64-bit int values, LP64 (32-bit int, 64-bit long) requires "%ld" and 32-bit platforms require "%lld". That's why you have e.g. the PRId64 macro from <inttypes.h> to select the correct format code for printing int64_t values. You could provide something similar to abstract away the required format code. If you're using the GNU C library you can even define custom format codes with register_printf_function(), which might be your only option if the calling convention for your template doesn't match any of the standard integer types.