如何打印uint64_t？失败：“格式为乱码尾随的'％'”； [英] How to printf uint64_t? Fails with: "spurious trailing ‘%’ in format"

问题描述

我写了一个非常简单的printf uint64_t测试代码：

I wrote a very simple test code of printf uint64_t:

#include <inttypes.h>
#include <stdio.h>

int main()
{
  uint64_t ui64 = 90;
  printf("test uint64_t : %" PRIu64 "\n", ui64);
  return 0;
}

我使用ubuntu 11.10（64位）和gcc版本4.6.1进行编译它，但失败了：

I use ubuntu 11.10 (64 bit) and gcc version 4.6.1 to compile it, but failed:

main.cpp: In function ‘int main()’:
main.cpp:9:30: error: expected ‘)’ before ‘PRIu64’
main.cpp:9:47: warning: spurious trailing ‘%’ in format [-Wformat]

推荐答案

ISO C99标准规定，只有在明确要求时才必须定义这些宏。

The ISO C99 standard specifies that these macros must only be defined if explicitly requested.

#define __STDC_FORMAT_MACROS
#include <inttypes.h>

... now PRIu64 will work

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