四舍五入到整数

Question

这个项目是为了获得所有实验室练习的平均水平。我想把我的小数7.7778除以整数。我尝试了ceilf和roundf()，它不起作用，我的代码有问题吗？任何帮助都将不胜感激，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!");
}

示例

输入实验室编号:3

实验室练习1: 10

实验练习2: 7

实验习题1: 6

平均实验室练习成绩为:7 //应该是8。

Answer 1

你的roundoff = ceilf(average * 100) / 100;错了

average被声明为int。

您应按以下方式声明：

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

看来你想做以下几件事：

#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

Answer 2

您应该使用以下代码来找到所需的平均值-

#include<stdio.h>
#include<conio.h>
#include <math.h>
int main()
{
int i,numberof_laboratory, lab_exercises, total_numberof_laboratory=0,roundoff;
float average;
char answer;
do
{
    printf("\nEnter number of laboratory:");
    scanf("%d",&numberof_laboratory);
    for(i=1;i<=numberof_laboratory;++i)
    {
        printf("\nEnter laboratory exercise %d:",i);
        scanf("%d",&lab_exercises);
        total_numberof_laboratory += lab_exercises;
    }
    average = (float)total_numberof_laboratory /numberof_laboratory ;
    roundoff = ceil(average);
    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!");
}

你应该把它看清楚，并注意到所做的改变。

1. 如果total_numberof_laboratory计数lab_exercises的总数，则必须用0值初始化它。
2. average应在计算和后计算。
3. 应该声明average浮点
4. 平均值是由average = (float)total_numberof_laboratory /numberof_laboratory ;计算的，而average = (float)total_numberof_laboratory / 3 ;做不到
5. 最后，只有ceil就足够了，不需要ceilf

乐意帮忙;-]