c - 想要在不将数据类型更改为 char 的情况下删除警告

Question

我想在不将数据类型更改为 char 的情况下删除警告。

#include<stdio.h>
#include<stdlib.h>
main()
{
    unsigned char ch;
    printf("Hello This is Problematic\n");
    scanf("%d",&ch);
    printf("1\n");
}

这会产生警告

test.c:7:2: warning: format ‘%d’ expects argument of type ‘int *’, but argument 2 has type ‘unsigned char *’ [-Wformat=] scanf("%d",&ch);

Answer 1

其实，

scanf("%d",&ch);

用 undefined behavior 离开你的程序因为提供的参数不是转换说明符的正确类型。你需要写

scanf("%hhu",&ch);

引用 C11，章节 §7.21.6.2

hh

Specifies that a following d, i, o, u, x, X, or n conversion specifier applies to an argument with type pointer to signed char or unsigned char.