C语言实现-读取文件的四则运算并计算

//文件版的四则运算
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include<string.h>

//进行文件四则运算的写入
void write_file()
{
    FILE* fp = NULL;
    fp = fopen("D:/C_sum/test.txt", "w");
    fputs("10/2=\n", fp);
    fputs("4-1=\n", fp);
    fputs("4*2=\n", fp);
    fputs("4+3=\n", fp);
    fclose(fp);
}

//利用switch语句求出四则运算的和
int Get_sum(int num1,char ch,int num2)
{
    int sum = 0;
    switch(ch)
    {
    case '+':
        sum = num1 + num2;
        return sum;
        break;
    case '-':
        sum = num1 - num2;
        return sum;
        break;
    case '*':
        sum = num1 * num2;
        return sum;
        break;
    case '/':
        sum = num1 / num2;
        return sum;
        break;
    }
}


//开始拼接字符串然后导入文件
void read_file(char str1[],char result[])
{
    FILE* fp = NULL;
    int sum;
    int num1, num2;
    char ch;
    fp = fopen("D:/C_sum/test.txt", "r");
    if (fp == NULL)
    {
        perror("OPEN file error:");
        return;
    }
    while (1)
    {

        char temp[4096];
        fgets(str1,4096, fp);    //读取一行字符串到str1中
        if (feof(fp))
            break;
        sscanf(str1, "%d%c%d=\n", &num1, &ch, &num2);//利用sscanf（）函数来按格式读取想要的数据
        sum = Get_sum(num1,ch,num2);    //调用求和函数来求出表达式的和
        sprintf(temp, "%d%c%d=%d\n", num1, ch, num2,sum);//利用Sprintf函数来格式化得到想要的字符串
        strcat(result, temp);    //利用strcat函数来拼接字符串

    }
    puts(result);
    fclose(fp);
    fp = fopen("D:/C_sum/test_sum.txt", "w");//最后打开文件来填写
    fputs(result, fp);
    fclose(fp);
}


int main()
{
    char result[4096] = { 0 };
    char str1[4096] = { 0 };
    read_file(str1,result);
    //write_file();
    return 0;
}