#include <stdio.h>
#include <string.h>
#include <stdlib.h>

//實現對文字內容的計算
//首先實現對文字中每一行內容的計算
int calcString(char *s){
    char num1[100] = {0};
    int oper = 0;
    char num2[100] = {0};
    //將讀取的字串進行拆分，擷取每一部分的內容
    int len = strlen(s);

    int i;
    for(i = 0; i < len; i++){
        if(s[i] == '+' || s[i] == '-' || s[i] == '*' || s[i] == '/'){
            strncpy(num1, s, i);
            oper = s[i];
            break;
        }
    }

    //確定第二個數字部分的擷取
    int start = i + 1;
    for(;i < len; i++){
        if(s[i] == '='){
            strncpy(num2, &s[start], i - start);
        }
    }

    //獲得計算的結果
    switch (oper) {
        case '+':
            return atoi(num1) + atoi(num2);
        case '-':
            return atoi(num1) + atoi(num2);
        case '*':
            return atoi(num1) + atoi(num2);
        case '/':
        {
            int temp = atoi(num2);
            if(temp)
                return atoi(num1) + atoi(num2);
            else
                return 0;
        }
    }
}

//去處每行末尾的換行符
void removeEnd(char *s){
    int len = strlen(s);
    if(s[len - 1] == '\n'){
        s[len - 1] = 0;
    }
}

int main(){
    //設定讀取檔案的字元緩衝區
    char buf[1024] = {0};
    char buf1[1024] = {0};
    //讀取檔案
    FILE *p = fopen("D:\\test\\a.txt", "r");
    FILE *p1 = fopen("D:\\test\\b.txt","w");
    while(!feof(p)){
        //然後讀取檔案的每一行進行計算
        memset(buf, 0, sizeof (buf));
        fgets(buf, sizeof(buf), p);

        //去處每行末尾的換行符
        removeEnd(buf);

        int value = calcString(buf);

        //將得到的內容進行組合
        memset(buf1, 0, sizeof (buf1));
        sprintf(buf1, "%s %d\n", buf, value);

        //將讀取出來的內容儲存到另一個檔案中
        fputs(buf1,p1);
    }

    fclose(p);
    fclose(p1);
    return 0;
}