c - scanf 无法识别格式 %zu

Question

我有以下代码:

#include <stdio.h>
#include <stdlib.h>

int compare(const void* a, const void* b)
{
    const int* x = a, *y = b;
    if (*x < *y)
        return -1;
    else if (*x == *y)
        return 0;
    else
        return 1;
}

int main()
{
    size_t n;
    printf("Enter number of numbers: ");
    scanf("%zu", &n); //<-- warnings here
    int numbers[n];
    for (size_t i = 0; i < n; i++)
    {
        printf("Enter number #%zu: ", i + 1); //NO warning here, printf works as expected
        scanf("%d", &numbers[i]);
    }
    qsort(numbers, n, sizeof *numbers, compare);
    for (size_t i = 0; i < n; i++)
        printf("%d ", numbers[i]);
    printf("\n");
    system("pause"); //don't comment for this, I know it's bad
}

我从 GCC 编译器收到 2 条警告:

warning: unknown conversion type character 'z' in format [-Wformat=]
warning: too many arguments for format [-Wformat-extra-args]

我已将 GCC 设置为 C11。谁能帮我理解为什么我会得到这个？

编辑:我忘了提及，即使有这些警告，我的代码仍然有效，但是对我来说很奇怪，变量 n 似乎没有从 scanf 获取其值

Answer 1

but I don't know how to check my compiler version

常见测试涉及__STDC__、__STDC_VERSION__。像这样的东西:

#if defined __STDC__
  #if defined __STDC_VERSION__ && __STDC_VERSION__ > 201710
    // New
    #error Time to update this code
  #elif defined __STDC_VERSION__ && __STDC_VERSION__ >= 201710
    #define CVERSION 2017
  #elif defined __STDC_VERSION__ && __STDC_VERSION__ >= 201112
    #define CVERSION 2011
  #elif defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901
    #define CVERSION 1999
  #elif defined __STDC_VERSION__ && __STDC_VERSION__ >= 199409
    #define CVERSION 1994
  #else
    #define CVERSION 1989
#else
    // Pre-standard C
    #define CVERSION 1972
#endif

<小时/>

“警告:格式 [-Wformat=] 中未知的转换类型字符 'z'”意味着使用旧的编译器。由于"%zu"是在C99中引入的。可能的条件编译。

size_t n;
printf("Enter number of numbers: ");
#if defined __STDC__ && defined __STDC_VERSION__ && __STDC_VERSION__ >= 199901
  scanf("%zu", &n);
#else
  unsigned long t;
  scanf("%lu", &t);
  n = t;
#endif

或者使用顶部的代码:

#if CVERSION >= 1999
  scanf("%zu", &n);
#else
  unsigned long t;
  scanf("%lu", &t);
  n = t;
#endif