题解 | #字母大小写转换#

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