C语言判断字符如果是大写则转换为小写

#include<stdio.h>
int main() {
    char ch, again;
    do {
        printf("输入一个字符！");
        ch = getchar();
        if (ch >= ‘A‘ && ch <= ‘Z‘) {
            printf("%c", ch + 32);
        }
        getchar();//无效回车符获取
        printf("\n还要继续吗？y或者Y继续：");
        again = getchar();
        getchar();
    } while ("‘y‘=again||‘Y‘=again");
    return 0;
}