在 do while 循环中调用 scanf 正在打破循环

Question

我有一个do while 循环。当我在没有scanf() 的情况下运行它时，它运行正常。但是，如果我输入 scanf() 它会打破循环！为什么？？？

代码：

scanf()

void main(){
    int num = prng() % 100, guessed, guesses = 0;
    bool  win = false;
    printf("The Game Begins. You Have To Guess A Number\n");
    do{ //A do while loop untill the user guesses the correct number
        printf("Guess a number\n");
        scanf("%d", guessed);
        guesses++;
    }while (!check(guessed, num));
    printf("Yayy!!! You won the game in %d guesses!!", guesses); //Message after guessing the correct number
    return;
}

这会立即打破循环：

> .\a.exe
The Game Begins. You Have To Guess A Number
Guess a number
5
> 

但是当我在没有 scanf() 的情况下运行它时

void main(){
    int num = prng() % 100, guessed, guesses = 0;
    bool  win = false;
    printf("The Game Begins. You Have To Guess A Number\n");
    do{ //A do while loop untill the user guesses the correct number
        printf("Guess a number\n");
        guessed = num;
        // scanf("%d", guessed);
        guesses++;
    }while (!check(guessed, num));
    printf("Yayy!!! You won the game in %d guesses!!", guesses); //Message after guessing the correct number
    return;
}

效果很好！！

> .\a.exe
The Game Begins. You Have To Guess A Number
Guess a number
Hurrayyy!!!! You got the number!!!!!!!!!Yayy!!! You won the game in 1 guesses!!
> 

你能解释一下实际的问题是什么吗？

Answer 1

您需要在scanf 函数内的guessed 变量前面添加&。

scanf("%d", &guessed);

scanf 工作原理的解释可见here。