思路

  1. 得到输入数据
  2. 将字符串中的字符不分大小写按顺序存到新数组
  3. 输出结果,原字符串中为大小写字母的用新字符串替换

Answer

#include<stdio.h>
#include<string.h>

int main() {
    char str[1001] = {0};
    int index = 0;
    gets(str);
    int len = strlen(str);
    char str_ch[len];
    for (char j = 'A'; j <= 'Z'; j++) {
        for (int i = 0; i < len; i++) {
            if ((str[i] == j)
                    || ( (str[i] - 32 == j)
                         && str[i] >= 'a' && str[i] <= 'z')) {
                str_ch[index++] = str[i];
            }
        }
    }
    index = 0;
    for (int i = 0; i < len; i++) {
        if ((str[i] >= 'a' && str[i] <= 'z') || (str[i] >= 'A' && str[i] <= 'Z')) {
            str[i] = str_ch[index++];
        }
        printf("%c", str[i]);
    }
    return 0;
}