5.7

#include<stdio.h>int main(){    char a;    printf("请输入一个字符：");    a=getchar();    if(a>=65&&a<=90)    {        a+=32;        putchar(a);        printf("  ASCLL的值为：%d",a);    }    else if(a>=97&&a<=122)    {        a-=32;        putchar(a);        printf("  ASCLL的值为：%d",a);    }    else    {        putchar(a);        printf("  ASCLL的值为：%d",a);    }}