Question

嘿伙计们我在c编程中有一个任务说：

“编写一个输入整数测试分数列表的C程序在0到100之间，并计算最高分数，最小分数得分和平均得分。使用-1作为标记来标记结尾输入。拒绝0到100范围之外的任何测试分数。您的程序还应该检测并拒绝错误的输入，例如字母和字符。您应该有一个读取和验证输入测试分数的函数并拒绝无效和错误的输入。这是一个示例运行“

我写了一段代码，但我的问题是如何拒绝像字符这样的输入..：

#include <stdio.h>
#define sentinel -1     // to end the program

int main ()
{
    int status, score, sum, i, max, min;
    double avrg;
    i = 0;          /* the counter */
    sum = 0;            // the total scores
    printf (" Enter the score , %d to termenate > ", sentinel);
    status = scanf ("%d", &score);  // checking the validity of the input

    max = score;        // the initial maximum
    min = score;        // the initial minimum

    while (score != sentinel) {

        while (score < 0 || score > 100)    // no negative or more than 100 score

        {
            printf ("The number is out of the range ; try again> ");
            scanf ("%d", &score);
        }

        sum = sum + score;
        i = i + 1;
        printf (" Enter the score , %d to termenate > ", sentinel);
        status = scanf ("%d", &score);
        if (score > max && score < 100)
            max = score;
        if (score < min && score > 0)
            min = score;
    }

    if (i != 0) {
        avrg = (double) sum / i;    // the sum of scores over the number of scores
        printf (" The avarage is : \n %.2f ", avrg);
        printf ("\n");
        printf (" Maximum score is : \n %d", max);
        printf ("\n");
        printf ("Minmum score is : \n %d", min);
    } else          // when the user ends the program without entering any value
    {
        printf ("You didn't enter any score");
    }

    return 0;
}

我希望你能帮助我

Answer 1

对多个输入使用scanf时，您需要注意几个条件。那些是matching失败和read失败。检查scanf返回允许您识别两者。如果在while循环中接受重复的整数输入，如果发生匹配失败，您还必须确保清空stdin以防止无限循环。有几种方法，但最简单的整数输入是在再次使用getchar之前，只需使用chars从stdin读取所有scanf。

以下是实施此方法的代码的快速示例：

#include <stdio.h>
#include <limits.h>     /* for INT_MAX */

#define SENTINEL -1     /* value to end the program         */
#define MAXSCORE 100    /* max input for score allowed      */

int main ()
{
    int status = 0;     /* always initialize you variables  */
    int score = 0;
    size_t sum = 0;     /* size_t for non-negative numbers  */
    size_t idx = 1;
    size_t max = 0;
    size_t min = INT_MAX;
    double avrg = 0.0;
    int c = 0;

    printf ("\n Enter scores [ '%d' to end entry ]\n", SENTINEL);

    while (printf ("\n  score: ") && (status = scanf ("%d", &score)) != -1)
    {
        /* check for matching failure, empty input buffer */
        if (status == 0) do { c = getchar(); } while ( c != '\n' && c != EOF);

        if (score == SENTINEL) break;
        if (score > MAXSCORE || score < 0) continue;

        if (score > max) max = score;
        if (score < min) min = score;

        sum += score;
        avrg = (double)sum/idx++;

        printf ("\n    minimum : %3zu\n    maximum : %3zu\n    average : %.2f\n", min, max, avrg);
    }

    printf ("\n Input complete\n\n");

    if (idx > 1)
        printf ("  number of scores : %3zu    Max score : %3zu    Min score : %3zu    Avg : %.2f\n\n",
                idx - 1, max, min, avrg);
    return 0;
}

<强>输出

$ ./bin/grades

 Enter scores [ '-1' to end entry ]

  score: 77

    minimum :  77
    maximum :  77
    average : 77.00

  score: 88

    minimum :  77
    maximum :  88
    average : 82.50

  score: 83

    minimum :  77
    maximum :  88
    average : 82.67

  score: -88

  score: 108

  score: G

  score: -1

 Input complete

  number of scores :   3    Max score :  88    Min score :  77    Avg : 82.67

Answer 2

也许您可以先输入字符串作为字符串，然后使用strtol检查无效字符？

例如Input validation of an Integer using atoi()

中的答案

计算最小，最大和平均测试分数输入验证

2 个答案: