5.7

#include <stdio.h>#include <stdlib.h>int main(){    char cf;    printf("输入英文字母：");    scanf("%c",&cf);    if(cf>='A'&&cf<='Z')    {   //     cf=getchar();//        cf=cf+32;        printf("%c,%d\n",cf,cf);    }    else if(cf>='a'&&cf<='z')    {     //   ch=getchar();//        cf=cf-32;        printf("%c,%d\n",cf,cf);    }    else    {        printf("%c\n",cf);    }}