题解 | #大小写转换#

#include <stdio.h>

int main() {
    char abc;
    while ((abc=getchar())!=EOF) { 
        if(abc >= 'A' && abc <= 'Z'){
            abc+=32;
        }else if(abc >= 'a' && abc <= 'z'){
            abc -= 32;
        }
        putchar(abc);
    }
    return 0;
}