C语言Hangman猜单词程序异常终止求助：输入提示后程序退出

我在用C语言编写Hangman（猜单词）游戏时遇到问题：程序打印出猜字母的提示后立即终止，首次猜测机会出现后没有后续输出。以下是程序代码、操作步骤及运行输出：

程序代码 #

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

int main() {
    char menu;
    int c = 0, flag = 0, life = 8;

    printf("\nWelcome to Hangman!!!");
    printf("\nThis is a game of hangman.");
    printf("Player 1 enters a random word and the other has to guess it.");
    printf("You get 8 lives in total i.e. you can have a maximum of 8 wrong guesses.");
    printf("\n");
    printf("Press n for new game\n");
    printf("Press q to quit\n");
    printf("\n");

    scanf("%c", &menu);
    int i = 0, j = 0;
    char w[20], ch;

    if (menu == 'q') {
        printf("Exiting...");
        printf("Thanks for playing");
    }
    else if (menu == 'n') {
        printf("Player 1 enters a word\n");
        scanf("%s", w);
        int len = strlen(w);

        for (int i = 0; i < len; i++) {
            toupper(w[i]);
        }

        printf("\e[1;1H\e[2J");
        char arr[len - 1];

        for (int i = 0; i < len - 1; i++) {
            arr[i] = '_';
            printf("%c", arr[i]);
        }

        printf("\n");

        while (life != 0) {
            for (int i = 0; i < len - 1; i++) {
                if (arr[i] == '_') {
                    flag = 1;
                    break;
                }
                else {
                    flag = 0;
                }
            }

            if (flag == 0) {
                printf("You Won!!\n");
                printf("You Guessed The Word: %s", w);
                break;
            }
            else {
                char ans;
                printf("Enter a letter between A-Z");
                scanf("%c", ans);
                toupper(ans);
                
                for (int j = 0; j < len; j++) {
                    if (ans == w[j]) {
                        arr[j] = ans;
                        c++;
                    }
                }

                if (c == 0) {
                    life--;
                }

                c = 0;

                for (int j = 0; j < len; j++) {
                    printf("%c", arr[j]);
                }

                printf("\n Lives Remaining= %d \n", life);
            }
        }

        if (life == 0) {
            printf("\n You Lost!!! \n");
            printf("The Word Was: %s", w);
        }
    }
    else {
        printf("Invalid Character");
    }
}

运行输出 #

Welcome to Hangman!!!
This is a game of hangman.Player 1 enters a random word and the other has to guess it.You get 8 lives in total i.e. you can have a maximum of 8 wrong guesses.
Press n for new game
Press q to quit

n
Player 1 enters a word
Hello

Enter a letter between A-Z
PS C:\Users\arora\Desktop\Programs\C>

问题原因及修复方案 #

1. scanf传参错误 #

scanf("%c", ans)未传递变量地址，会触发未定义行为导致程序崩溃，需改为scanf("%c", &ans)。

2. 输入缓冲区残留换行符 #

读取单词的scanf("%s", w)会在缓冲区留下换行符，后续scanf("%c", &ans)会直接读取该换行符，跳过用户输入。解决方法：在scanf前加空格忽略空白字符，即scanf(" %c", &ans)。

3. toupper函数未赋值返回值 #

toupper(w[i])和toupper(ans)仅计算大写值但未赋值回原变量，导致大小写匹配失效。需修改为：

w[i] = toupper(w[i]);
ans = toupper(ans);

同时需包含头文件#include <ctype.h>，否则toupper无法正常工作。

4. 数组arr长度不足 #

char arr[len - 1];长度比单词短1，会导致越界访问。应改为char arr[len];，初始化循环也需遍历到len：

for (int i = 0; i < len; i++) {
    arr[i] = '_';
    printf("%c", arr[i]);
}

5. 胜利判断逻辑遗漏最后一个字符 #

胜利判断循环仅检查到len-1，最后一个字符未被验证，导致无法正确触发胜利条件。修改循环为：

for (int i = 0; i < len; i++) {
    if (arr[i] == '_') {
        flag = 1;
        break;
    } else {
        flag = 0;
    }
}

修复后的完整代码 #

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

int main() {
    char menu;
    int c = 0, flag = 0, life = 8;

    printf("\nWelcome to Hangman!!!");
    printf("\nThis is a game of hangman.");
    printf(" Player 1 enters a random word and the other has to guess it.");
    printf(" You get 8 lives in total i.e. you can have a maximum of 8 wrong guesses.");
    printf("\n");
    printf("Press n for new game\n");
    printf("Press q to quit\n");
    printf("\n");

    scanf("%c", &menu);
    int i = 0, j = 0;
    char w[20];

    if (menu == 'q') {
        printf("Exiting...");
        printf(" Thanks for playing");
    }
    else if (menu == 'n') {
        printf("Player 1 enters a word\n");
        scanf("%s", w);
        int len = strlen(w);

        // 将单词转为大写
        for (int i = 0; i < len; i++) {
            w[i] = toupper(w[i]);
        }

        printf("\e[1;1H\e[2J");
        // 初始化与单词长度一致的下划线数组
        char arr[len];
        for (int i = 0; i < len; i++) {
            arr[i] = '_';
            printf("%c ", arr[i]);
        }
        printf("\n");

        while (life != 0) {
            flag = 0;
            // 检查是否还有未猜中的字符
            for (int i = 0; i < len; i++) {
                if (arr[i] == '_') {
                    flag = 1;
                    break;
                }
            }

            if (!flag) {
                printf("\nYou Won!!\n");
                printf("You Guessed The Word: %s\n", w);
                break;
            }
            else {
                char ans;
                printf("Enter a letter between A-Z: ");
                // 用空格忽略缓冲区的空白字符
                scanf(" %c", &ans);
                ans = toupper(ans);
                
                c = 0;
                for (int j = 0; j < len; j++) {
                    if (ans == w[j]) {
                        arr[j] = ans;
                        c++;
                    }
                }

                if (c == 0) {
                    life--;
                    printf("Wrong guess!\n");
                }

                // 打印当前猜测进度
                printf("Current progress: ");
                for (int j = 0; j < len; j++) {
                    printf("%c ", arr[j]);
                }
                printf("\nLives Remaining: %d\n", life);
            }
        }

        if (life == 0) {
            printf("\nYou Lost!!!\n");
            printf("The Word Was: %s\n", w);
        }
    }
    else {
        printf("Invalid Character\n");
    }
    return 0;
}

内容的提问来源于stack exchange，提问作者AnimalPlayer258