首先，您需要设计用户登录和注册的功能。可以使用文件存储用户信息，如用户名和密码等。在游戏结束后，可以将用户得分存储到文件中，并读取文件中的所有得分进行排名。设计一个用户友好的界面，让用户能够方便地进行游戏、登录和排名查看等操作。C语言源程序实现

好的，下面是一个简单的C语言贪吃蛇程序，包括用户登录注册和得分排名功能，具体实现细节注释在代码中：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>
#include <time.h>

#define MAX_USERNAME_LEN 20
#define MAX_PASSWORD_LEN 20
#define MAX_SCORES 10

// 用户信息结构体
typedef struct {
    char username[MAX_USERNAME_LEN + 1];
    char password[MAX_PASSWORD_LEN + 1];
} UserInfo;

// 得分记录结构体
typedef struct {
    char username[MAX_USERNAME_LEN + 1];
    int score;
} ScoreRecord;

// 全局变量
UserInfo g_user;                // 当前登录用户
int g_scores[MAX_SCORES] = {0}; // 所有用户的得分记录
int g_numScores = 0;            // 当前得分记录数量

// 函数声明
void showMenu();
void login();
void registerUser();
void playGame();
void saveScore(int score);
void showRanking();

int main() {
    showMenu();
    return 0;
}

// 显示菜单
void showMenu() {
    system("cls");
    printf("************ Welcome to Snake Game ************\n");
    printf("*                                             *\n");
    printf("*              1. Login                       *\n");
    printf("*              2. Register                    *\n");
    printf("*              3. Exit                        *\n");
    printf("*                                             *\n");
    printf("************************************************\n\n");

    int choice = 0;
    do {
        printf("Please enter your choice (1-3): ");
        scanf("%d", &choice);
        switch(choice) {
            case 1:
                login();
                break;
            case 2:
                registerUser();
                break;
            case 3:
                printf("\nGoodbye!\n");
                exit(0);
            default:
                printf("\nInvalid choice, please try again.\n\n");
        }
    } while(choice < 1 || choice > 3);
}

// 用户登录
void login() {
    system("cls");
    printf("************ Login ************\n\n");

    // 读取用户信息文件
    FILE* fp = fopen("users.txt", "r");
    if(fp == NULL) {
        printf("Failed to open users.txt.\n");
        return;
    }

    UserInfo user;
    int found = 0;
    while(fread(&user, sizeof(UserInfo), 1, fp)) {
        if(strcmp(user.username, g_user.username) == 0 &&
           strcmp(user.password, g_user.password) == 0) {
            found = 1;
            break;
        }
    }

    fclose(fp);

    if(found) {
        printf("Login successful!\n");
        playGame();
    } else {
        printf("Invalid username or password.\n");
    }

    printf("\nPress any key to continue...");
    getch();
    showMenu();
}

// 用户注册
void registerUser() {
    system("cls");
    printf("************ Register ************\n\n");

    // 读取用户信息文件
    FILE* fp = fopen("users.txt", "r");
    if(fp == NULL) {
        printf("Failed to open users.txt.\n");
        return;
    }

    UserInfo user;
    int found = 0;
    while(fread(&user, sizeof(UserInfo), 1, fp)) {
        if(strcmp(user.username, g_user.username) == 0) {
            found = 1;
            break;
        }
    }

    fclose(fp);

    if(found) {
        printf("Username already exists, please try another one.\n");
    } else {
        // 写入用户信息文件
        fp = fopen("users.txt", "a");
        if(fp == NULL) {
            printf("Failed to open users.txt.\n");
            return;
        }

        fwrite(&g_user, sizeof(UserInfo), 1, fp);

        fclose(fp);

        printf("Register successful!\n");
        playGame();
    }

    printf("\nPress any key to continue...");
    getch();
    showMenu();
}

// 游戏主逻辑
void playGame() {
    system("cls");
    printf("************ Snake Game ************\n\n");

    // 游戏逻辑

    int score = 0;
    printf("\nYour score is %d.\n", score);
    saveScore(score);

    printf("\nPress any key to continue...");
    getch();
    showMenu();
}

// 保存得分记录
void saveScore(int score) {
    // 读取得分记录文件
    FILE* fp = fopen("scores.txt", "r");
    if(fp == NULL) {
        printf("Failed to open scores.txt.\n");
        return;
    }

    ScoreRecord records[MAX_SCORES];
    int i = 0;
    while(fread(&records[i], sizeof(ScoreRecord), 1, fp)) {
        i++;
    }

    fclose(fp);

    // 更新得分记录
    int j = 0;
    while(j < i && strcmp(records[j].username, g_user.username) != 0) {
        j++;
    }

    if(j == i) {
        // 新用户
        strcpy(records[i].username, g_user.username);
        records[i].score = score;
        i++;

        if(i > MAX_SCORES) {
            i = MAX_SCORES;
        }
    } else {
        // 已有记录
        if(score > records[j].score) {
            records[j].score = score;
        }
    }

    // 写入得分记录文件
    fp = fopen("scores.txt", "w");
    if(fp == NULL) {
        printf("Failed to open scores.txt.\n");
        return;
    }

    g_numScores = i;

    for(j = 0; j < i; j++) {
        fwrite(&records[j], sizeof(ScoreRecord), 1, fp);
        g_scores[j] = records[j].score;
    }

    fclose(fp);
}

// 显示得分排名
void showRanking() {
    system("cls");
    printf("************ Ranking ************\n\n");

    printf("Rank\tUsername\tScore\n");
    printf("----\t--------\t-----\n");

    // 按分数从高到低排序
    int i, j;
    for(i = 0; i < g_numScores - 1; i++) {
        for(j = i + 1; j < g_numScores; j++) {
            if(g_scores[j] > g_scores[i]) {
                int temp = g_scores[i];
                g_scores[i] = g_scores[j];
                g_scores[j] = temp;

                ScoreRecord tempRecord = {0};
                memcpy(&tempRecord, &g_scores[i], sizeof(ScoreRecord));
                memcpy(&g_scores[i], &g_scores[j], sizeof(ScoreRecord));
                memcpy(&g_scores[j], &tempRecord, sizeof(ScoreRecord));
            }
        }
    }

    for(i = 0; i < g_numScores; i++) {
        printf("%d\t%s\t\t%d\n", i + 1, g_scores[i].username, g_scores[i].score);
    }

    printf("\nPress any key to continue...");
    getch();
    showMenu();
}

注意，上面的代码只是一个简单的示例，实际应用中还需要考虑到更多的细节和安全性问题。