计算不正常

Question

我正在从一本名为“C by Example”的书中学习C

每章结尾都有一个练习要完成。从下面的代码中可以看出，练习写在顶部

/* Chapter 7 Review Exercises #2
- You are a college professor and you have to get the average grades for 10 students. Write a program which prompts you for 10 different grades and then
displays their average */

#include <stdio.h>

int main()
{

    float score1, score2, score3, score4, score5, score6, score7, score8, score9, score10;

    float average = score1+score2+score3+score4+score5+score6+score7+score8+score9+score10/10;

    printf("Please input the scores of the students: \n");
    scanf(" %f",&score1);
    scanf(" %f",&score2);
    scanf(" %f",&score3);
    scanf(" %f",&score4);
    scanf(" %f",&score5);
    scanf(" %f",&score6);
    scanf(" %f",&score7);
    scanf(" %f",&score8);
    scanf(" %f",&score9);
    scanf(" %f",&score10);

    printf("The average score is: %.2f" , average);

    return 0;

}

这里的问题是每次我输入数字（运行代码时）它总是给我一个巨大的数字（至少20个数字）

有没有办法限制数量，或者我做错了什么？

Answer 1

你在这里遗漏了一些括号：

float average = score1+score2+score3+score4+score5+score6+score7+score8+score9+score10/10;

将其更改为：

float average = (score1+score2+score3+score4+score5+score6+score7+score8+score9+score10)/10;

您还需要将此行向下移动，以便在输入阶段之后（即在所有对scanf的调用之后），因为尝试计算某些内容是没有意义的之前您拥有所有输入值。

您可能想要了解运算符优先级，也可以循环，因为您的程序可以更简单，更简洁地编写：

#include <stdio.h>

int main()
{
    const int n = 10;
    float sum = 0.0f;
    float average;
    int i;

    printf("Please input the scores of the students: \n");

    for (i = 0; i < n; ++i)
    {
        float score;

        scanf(" %f", &score);
        sum += score;
    }

    average = sum / n;

    printf("The average score is: %.2f" , average);

    return 0;
}

Answer 2

这个数字确实是错误的，因为你不了解C如何执行代码。它最适合botom。因此，如果您需要得分1 ...得分10的值，则首先需要执行scanf，然后才能使用+。

Answer 3

以下代码可以使用。您的代码无法正常工作，因为您尝试在扫描之前计算数字。仍然需要记住，C保持操作的顺序，因此/在+之前执行。添加缺少的括号()。在C中，代码从顶部到底部处理！

#include <stdio.h>
int main() {

    float score1, score2, score3, score4, score5, score6, score7, score8, score9, score10;

    printf("Please input the scores of the students: \n");
    scanf(" %f",&score1);
    scanf(" %f",&score2);
    scanf(" %f",&score3);
    scanf(" %f",&score4);
    scanf(" %f",&score5);
    scanf(" %f",&score6);
    scanf(" %f",&score7);
    scanf(" %f",&score8);
    scanf(" %f",&score9);
    scanf(" %f",&score10);

    float average = (score1+score2+score3+score4+score5+score6+score7+score8+score9+score10)/10;
    printf("The average score is: %.2f" , average);

    return 0;

}