题解 | #字母大小写转换#

#include <stdbool.h>
#include <stdio.h>

int main() {
    int ch;
    while((ch=getchar()) != EOF)
    {
        if (('a' <= ch) && (ch <= 'z'))
        {
            printf("%c\n", (ch-32));
        }
        if (('A' <= ch) && (ch <= 'Z'))
        {
            printf("%c\n", (ch+32));
        }
    }
    return 0;
}