C语言常用函数-toupper()将字符转换为大写英文字母函数

int toupper(int ch);

#include <stdio.h>
#include <ctype.h>

int main()
{
    char ch1, ch2;
    printf("input a character\n");
    scanf_s("%c", &ch1);
    ch2 = toupper(ch1);
    printf("transform %c to %c\n", ch1, ch2);

    return 0;
}