更高/更低的博弈 - 如何在 while 循环中检查输入是否为整数-解网

问：

当我的代码检查输入是整数还是字符串时，它会进入输出“无效输入”和“猜测 0-9 之间的数字”的无限循环，而不会给用户输入新内容的机会。

下面的代码是我所拥有的

// Created on: Oct 2023    
// This program allows the user to guess a number between 0-9  
#include <stdlib.h>  
#include <stdio.h>  
#include <time.h>  

int main() {  
    // this function allows the user to guess a number  
    // and the program decides if the user is correct  

    unsigned int seed = time(NULL);  
    int randomNumber = rand_r(&seed) % 9;  
    int num = 0;  
    int scanerrorcode = 0;  
    
    while (1)  
    {  
        printf("\nGuess a number between 0-9: ");  
        scanf("%d", &num);
        if (num < 0 || num > 9) {
            printf("\n%d is not between 0-9", num);
        } else if (num == randomNumber) {
            printf("\nYou guessed correctly!");
            break;
        } else if (num > randomNumber) {  
            printf("\nYou guessed too high!");  
        } else if (num < randomNumber) {  
            printf("\nYou guessed too low!");  
        } else {  
            printf("\nError, %d is not a number", num);  
        }  
    }  

    printf("\nDone.");  
}

我正在寻找一种方法来制作这个游戏，只使用 while 循环和 break 语句。代码应不断要求用户输入，直到猜到随机数

c if 语句 while-loop 整数中断

"检查输入是整数还是字符串“ 不，它不是。当调皮的用户进入时不满意，所以它把它留在输入缓冲区中，只是为了一次又一次地找到它。了解如何在一次操作中使用和清空缓冲区，并验证用户的输入是否是程序正常工作所需的内容。远离 .它不适合初学者......scanf()"foobar"fgets()strtol()scanf()

答：

-1赞 Matthew Sexton 11/6/2023 #1

当您尝试输入一个不是 0 到 9 的值（因此像 a、b、c 等字符）时，您会得到垃圾值，您需要将其作为 char 获取并通过应用偏移量将其转换为 asci ii 值。

int main() {  
unsigned int seed = time(NULL);
int randomNumber = rand_r(&seed) % 9;
int scanerrorcode = 0;

while (1)
{
    int num = 0; //need to reset ever time we loop
    char ch;
    printf("\nGuess a number between 0-9: ");  
    scanf(" %c", &ch);  

    //ascii 2 char for 0 - 9 is 48 - 57! https://www.ascii-code.com/
    printf("The ASCII value of %c is %d \n", ch, ch);

    // To make a digit
    num = num * 10 + (ch - 48);

    //Hey look it's valid!
    if (ch >= 48 && ch <= 57) {
        printf("\n%d is valid and between 0-9", num);
    }

    //not valid!
    if (ch> 57 || ch < 48){
        printf("\n%d is NOT between 0-9!", num);
    } else if (num == randomNumber) {
        printf("\nYou guessed correctly!");
        break;
    } else if (num > randomNumber) {
        printf("\nYou guessed too high!");
    } else if (num < randomNumber) {
        printf("\nYou guessed too low!");
    } else {
        printf("\nError, %d is not a number", num);
    }
}  

printf("\nDone.");

}

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

int main() {
    // This function allows the user to guess a number
    // and the program decides if the user is correct

    int i;
    unsigned int seed = time(NULL);
    int randomNumber = rand_r(&seed) % 9;
    char num[5];

    while (1)
    {
        printf("Guess a number between 0-9: ");
        i = scanf("%s", num);                                   /* Input user entry into a character array                          */

        for (i = 0; i < strlen(num); i++)                       /* Ensure no non-digits are entered in the for loop test            */
        {
            if ((isdigit(num[i]) == 0))
                break;
        }

        if ((isdigit(num[i]) == 0) && (i < strlen(num))) {
            printf("Error, %s is not a number\n", num);       /* Move non-digit test as the first test                            */
            continue;
        }

        i = atoi(num);                                          /* Use conventional string function to convert string to an integer */

        if ((i < 0) || (i > 9)) {
            printf("%d is not between 0 - 9\n", i);
        } else if (i == randomNumber) {
            printf("You guessed correctly!\n");
            break;
        } else if (i > randomNumber) {
            printf("You guessed too high!\n");
        } else {
            printf("You guessed too low!\n");
        }
    }

    printf("Done.\n");

    return 0;
}

添加了评论，但这里有一些关键点。

添加了“string.h”和“ctype.h”包含文件以利用标准字符操作。
在“scanf”函数中，使用字符数组代替整数进行数据输入（请注意，没有与号）。
然后验证字符数组条目，确保仅输入数字，输入的值在猜测范围内，然后猜测相对于随机数的位置。

接下来是在终端进行试运行。

craig@Vera:~/C_Programs/Console/Guess/bin/Release$ ./Guess 
Guess a number between 0-9: huh
Error, huh is not a number
Guess a number between 0-9: 11
11 is not between 0 - 9
Guess a number between 0-9: 5
You guessed too high!
Guess a number between 0-9: 2
You guessed too low!
Guess a number between 0-9: 3
You guessed correctly!
Done.

从中得到的启示可能是参考一些关于字符串和字符函数用法的优秀教程文献。

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