在C中显示最大值和最小值

时间：2012-05-29 22:47:42

标签： c

我遇到显示最低平均值的问题。我已经终止了考试成绩输入的终止价值。当我触发-999并显示最低考试分数时，我会收到-999而不是实际最低分数的值。如何排除此值？

这是我的代码：

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
{
    int menuChoice, scoreCount = 0;
    float examScore = 0.0, 
          maxScore = 0.0,
          minScore = 0.0, 
          avgScore = 0.0, 
          sumScore = 0.0;

    printf("************************************\n");
    printf("1-> Enter an Exam Score\n");
    printf("2-> Display the highest exam score\n");
    printf("3-> Display the lowest exam score\n");
    printf("4-> Display the average exam score\n");
    printf("5-> Quit the program\n");
    printf("************************************\n\n");

    printf("Select a number that corresponds to the menu :\n");
    scanf("%d", &menuChoice);

    while(menuChoice != 5) 
    {
        switch(menuChoice)
        {
        case 1:
            while(examScore != -999)
            {
                printf("Enter an exam score (enter -999 to quit score input):\n");
                scanf("%f", &examScore);
                printf("The score you've entered equates to : %.2f\n\n", examScore);
                scoreCount++;

                if(maxScore < examScore)
                {
                    maxScore = examScore;
                }
                if(minScore > examScore)
                {
                    minScore = examScore;
                }
                else if(examScore < 0 || examScore > 100)
                {
                  printf("Exam Scores range from 0.0 - 100.0\n");
                }
                sumScore += examScore;
                avgScore = sumScore / scoreCount;
            }
            break;

        case 2:
            printf("The highest exam score is : %.2f\n", maxScore);
            break;

        case 3:
            printf("The lowest exam score is : %.2f\n", minScore);
            break;

        case 4:
            printf("The average exam score is : %.2f", avgScore);              
            break;

        default:
            printf("You've entered an invalid menu choice, review more carefully!");
            break;
        }

        printf("Select a number that corresponds to the menu :\n");
        scanf("%d", &menuChoice);
    } 

    system("pause");
    return 0;
}

7 个答案:

答案 0 :(得分：1)

修复while循环的逻辑。您在检查minScore是否为-999之前更新examScore，这样做不好。

此外，您应该在使用之前初始化examScore之类的变量，并且不应该使用浮点数对examScore != -999进行精确比较。要么更改为整数，要么进行更宽容的比较，例如examScore < -998。

答案 1 :(得分：1)

考虑以下计划。会do_stuff被调用吗？

int foo;
while (foo != 5) {
   foo = 5;
   do_stuff();
}

实际上行为是未定义的，因为foo在初始化之前已经过测试。您的代码与examScore具有相同的问题。由于这是作业，这只是一个提示 - 你如何修复上面的简单程序？

答案 2 :(得分：0)

该代码的问题在于，当用户输入-999时，它会将其作为测试分数进行处理。循环需要重新构建，以便在用户输入后立即中断。

答案 3 :(得分：0)

与其他人一样，您在处理完该分数后会对-999进行检查。另外我假设你应该只在当前考试较低时更新minScore所以你应该有类似的东西：

if(maxScore < examScore)
{
    maxScore = examScore;
}

if(minScore > examScore)
{
   minScore = examScore;
}

最后，您应该在使用之前初始化所有变量。

编辑：

while(...) 
   printf("Enter an exam score (enter -999 to quit score input):\n");
   scanf("%f", &examScore);
   printf("The score you've entered equates to : %.2f\n\n", examScore);

   if(examScore < 0 || examScore > 100)
   {
       printf("Exam Scores range from 0.0 - 100.0\n");
       continue; //goes back to the top of the loop skipping everything else
   } 
   //At this point you know the score is valid so you can process it
   scoreCount++;

   if(maxScore < examScore)
   {
       maxScore = examScore;
   }
   if(minScore > examScore)
   {
      minScore = examScore;
   }
   sumScore += examScore;
   avgScore = sumScore / scoreCount;
}

如果它不在循环中或您不想使用continue，您可以在有效性检查后将其他所有内容（所有处理内容）放在else块中。

答案 4 :(得分：0)

除了没有init的值之外还有一个逻辑错误，并且直接比较拖曳浮点问题。 在你的情况下1 while循环，你需要确定用户输入是否首先满足终止条件，然后处理它。另外minScore需要在分配之前进行比较，就像twain249所说的那样。

答案 5 :(得分：0)

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
{
    int scoreCount = 0;
    float maxScore = -1000.0,
          minScore = 1000.0,
          sumScore = 0.0;

    printf("************************************\n");
    printf("1-> Enter Exam Scores\n");
    printf("2-> Display the highest exam score\n");
    printf("3-> Display the lowest exam score\n");
    printf("4-> Display the average exam score\n");
    printf("5-> Quit the program\n");
    printf("************************************\n\n");

    for(;;)
    {
        int menuChoice;
        printf("Select a number that corresponds to the menu:\n");
        scanf("%d", &menuChoice);

        if(scoreCount == 0 && menuChoice >= 2 && menuChoice <= 4)
        {
            printf("Please enter some scores by choosing menu item 1\n");
            continue;
        }

        switch(menuChoice)
        {
        case 1:
            for(;;)
            {
                float examScore;
                printf("Enter an exam score (enter -999 to quit score input):\n");
                scanf("%f", &examScore);
                if (examScore == -999)
                    break;
                printf("The score you've entered equates to : %.2f\n\n", examScore);
                if(examScore < 0 || examScore > 100)
                {
                    printf("Exam scores range from 0.0 - 100.0\n");
                    continue;
                }

                sumScore += examScore;
                ++scoreCount;

                if(maxScore < examScore)
                {
                    maxScore = examScore;
                }
                if(minScore > examScore)
                {
                    minScore = examScore;
                }
            }
            break;

        case 2:
            printf("The highest exam score is : %.2f\n", maxScore);
            break;

        case 3:
            printf("The lowest exam score is : %.2f\n", minScore);
            break;

        case 4:
        {
            float avgScore = sumScore / scoreCount;
            printf("The average exam score is : %.2f\n", avgScore);
            break;
        }

        default:
            printf("You've entered an invalid menu choice, review more carefully!");
            break;
        }
    }

    return 0;
}

答案 6 :(得分：0)

有两个问题：负分数存储为最小值，但是当修正时，最小分数的初始值将为0，因此您无法获得更高的值。 如果min-check的输入不超过100（代码注释中为initA）或初始值为第一个值（基于分数计数 - initB），则将最小分数初始化为100。 输入考试分数也可以通过简单地提供超出范围的值来退出：

float minScore = 100.0; /* initA */
/* .. */
    case 1 :
    {
        printf("Enter an exam score (0..100): "); scanf("%f", &examScore);
        while( ( 0.0 <= examScore ) && ( examScore <= 100.0 ) )
        {
            if( 0 == scoreCount ) { minScore = examScore; } /* initB */
            ++scoreCount;
            if( maxScore < examScore ) { maxScore = examScore; }
            if( minScore < examScore ) { minScore = examScore; }
            sumScore += examScore;
            avgScore = sumScore / scoreCount;
            printf("Enter an exam score (0..100): "); scanf("%f", &examScore);
        }
        break;
    }

并非所有printf都以\n关闭。

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