用C语言编写简单的Caesar密码程序

#include <stdio.h>

// 函数用于加密消息
void encrypt(char message[], int key) {
    int i = 0;
    char ch;

    while (message[i] != '\0') {
        ch = message[i];

        // 对字母进行加密
        if (ch >= 'a' && ch <= 'z') {
            ch = ch + key;

            if (ch > 'z') {
                ch = ch - 'z' + 'a' - 1;
            }

            message[i] = ch;
        }
        else if (ch >= 'A' && ch <= 'Z') {
            ch = ch + key;

            if (ch > 'Z') {
                ch = ch - 'Z' + 'A' - 1;
            }

            message[i] = ch;
        }

        i++;
    }
}

int main() {
    char message[100];
    int key;

    printf("请输入要加密的消息：");
    fgets(message, sizeof(message), stdin);

    printf("请输入加密的偏移量：");
    scanf("%d", &key);

    encrypt(message, key);

    printf("加密后的消息为：%s\n", message);

    return 0;
}