编辑代码

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

#define ROW 6
#define COL 6
#define MAX_LEN 1000

char chessboard[ROW][COL] = {
    {'a', 'b', 'c', 'd', 'e', 'f'},
    {'g', 'h', 'i', 'j', 'k', 'l'},
    {'m', 'n', 'o', 'p', 'q', 'r'},
    {'s', 't', 'u', 'v', 'w', 'x'},
    {'y', 'z', '0', '1', '2', '3'},
    {'4', '5', '6', '7', '8', '9'}
};

void encrypt(char *plaintext, char *ciphertext) {
    int i, j, k, x, y, len;
    len = strlen(plaintext);
    k = 0;
    for (i = 0; i < len; i++) {
        if (isalpha(plaintext[i])) {
            plaintext[i] = tolower(plaintext[i]);
            for (j = 0; j < ROW; j++) {
                for (k = 0; k < COL; k++) {
                    if (chessboard[j][k] == plaintext[i]) {
                        x = j;
                        y = k;
                        break;
                    }
                }
            }
            if (x == ROW - 1) {
                x = 0;
            } else {
                x++;
            }
            ciphertext[i] = chessboard[x][y];
        } else {
            ciphertext[i] = plaintext[i];
        }
    }
    ciphertext[i] = '\0';
}

void decrypt(char *ciphertext, char *plaintext) {
    int i, j, k, x, y, len;
    len = strlen(ciphertext);
    k = 0;
    for (i = 0; i < len; i++) {
        if (isalpha(ciphertext[i])) {
            ciphertext[i] = tolower(ciphertext[i]);
            for (j = 0; j < ROW; j++) {
                for (k = 0; k < COL; k++) {
                    if (chessboard[j][k] == ciphertext[i]) {
                        x = j;
                        y = k;
                        break;
                    }
                }
            }
            if (x == 0) {
                x = ROW - 1;
            } else {
                x--;
            }
            plaintext[i] = chessboard[x][y];
        } else {
            plaintext[i] = ciphertext[i];
        }
    }
    plaintext[i] = '\0';
}

int main() {
    char plaintext[MAX_LEN], ciphertext[MAX_LEN], decrypted[MAX_LEN];
    printf("请输入明文：");
    fgets(plaintext, MAX_LEN, stdin);
    plaintext[strlen(plaintext)-1] = '\0'; // 去掉输入字符串的换行符
    encrypt(plaintext, ciphertext);
    printf("加密后的密文：%s\n", ciphertext);
    decrypt(ciphertext, decrypted);
    printf("解密后的明文：%s\n", decrypted);
    return 0;
}