[求助从键盘输入一个大写字母，要求改用小写字母输出..
...
main(){
char big;
printf("Input the up zimu:");
scanf("%c",&big);
while(big>'Z' || big <'A'){
printf("Error!Input the up zimu:");
scanf("%c",&big);
}
printf("%c\n",big-a+A);
}
