Why Am I Getting Compilation Errors When Using "%u64" in Printf?

Understanding "%u64" in "Printf" and Resolving Compilation Issues

When attempting to print a 64-bit unsigned integer using "printf" with the "%u64" format specifier, some users encounter compilation errors. This error stems from the fact that these format specifiers are not defined in the standard C library by default.

To resolve this issue, it is necessary to explicitly enable these format specifiers by defining the "__STDC_FORMAT_MACROS" macro before including the "inttypes.h" header. Here's an example of how to do this:

#define __STDC_FORMAT_MACROS
#include <inttypes.h>

// Rest of your code...

printf("test uint64_t : %" PRIu64 "\n", ui64);

After adding this line to the top of your code, the compiler will recognize the "%u64" format specifier and generate the correct code to print the 64-bit unsigned integer without any errors. This is because the "__STDC_FORMAT_MACROS" macro ensures that the format macros, including "%u64", are included in the C standard library.

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