c - 四舍五入为整数

Question

该程序是关于获取所有实验室练习的平均值。我想将小数点 7.7778 四舍五入为整数。我尝试了 ceilf 和 roundf() 它不起作用，我的代码有什么问题吗？任何帮助将不胜感激谢谢!

我的代码

#include<stdio.h>
#include<conio.h>
#include <math.h>
int main()
{
    int numberof_laboratory,lab_exercises,total_numberof_laboratory,average,roundoff;
    char answer;
    do
    {
        printf("\nEnter number of laboratory:");
        scanf("%d",&numberof_laboratory);
        for(int i=1;i<=numberof_laboratory;++i)
        {
            printf("\nEnter laboratory exercise %d:",i);
            scanf("%d",&lab_exercises);
            total_numberof_laboratory += lab_exercises;
            average = total_numberof_laboratory / 3;
            roundoff = ceilf(average * 100) / 100;
        }
        printf("The average laboratory exercise grade is %d",roundoff);
        printf("\nDo you want to continue(Y/N)?");
        scanf(" %c", &answer);
    }
    while(answer != 'N' && answer != 'n');
    printf("Goodbye!");
}

例子

输入实验室数量:3

实验室练习 1:10

实验室练习 2:7

实验室练习 1:6

实验室作业平均分是:7//应该是8

Answer 1

您的 roundoff = ceilf(average * 100)/100; 是错误的

average 声明为 int。

你应该声明如下:

float average;
...
average = total_numberof_laboratory / 3.0f; // thanks to Ed Heal
roundoff = roundf(average);

您似乎想要以下内容:

#include <stdio.h>
#include <math.h>
int main()
{
    int numberof_laboratory, lab_exercises, total_numberof_laboratory, roundoff;
    float average; /* see here */
    char answer;
    do
    {
        printf("\nEnter number of laboratory:");
        scanf("%d",&numberof_laboratory);
        total_numberof_laboratory = 0; /* see here important */
        for(int i=1;i<=numberof_laboratory;++i)
        {
            printf("\nEnter laboratory exercise %d:",i);
            scanf("%d",&lab_exercises);
            total_numberof_laboratory += lab_exercises;
        }
        average = total_numberof_laboratory / (float)numberof_laboratory; /* see here */
        roundoff = roundf(average); /* see here */
        printf("The average laboratory exercise grade is %d",roundoff);
        printf("\nDo you want to continue(Y/N)?");
        scanf(" %c", &answer);
    }
    while(answer != 'N' && answer != 'n');
    printf("Goodbye!");
}

在 gcc 中编译为

gcc -o main main.c -lm  -Wall -pedantic