//檔案版的四則運算
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include<string.h>

//進行檔案四則運算的寫入
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語句求出四則運算的和
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;
    }
}


//開始拼接字串然後匯入檔案
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);    //讀取一行字串到str1中
        if (feof(fp))
            break;
        sscanf(str1, "%d%c%d=\n", &num1, &ch, &num2);//利用sscanf（）函式來按格式讀取想要的資料
        sum = Get_sum(num1,ch,num2);    //呼叫求和函式來求出表示式的和
        sprintf(temp, "%d%c%d=%d\n", num1, ch, num2,sum);//利用Sprintf函式來格式化得到想要的字串
        strcat(result, temp);    //利用strcat函式來拼接字串

    }
    puts(result);
    fclose(fp);
    fp = fopen("D:/C_sum/test_sum.txt", "w");//最後開啟檔案來填寫
    fputs(result, fp);
    fclose(fp);
}


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