(C/C++) FILE 讀寫檔案操作

在C/C++ 讀寫檔案操作比較常見應該是利用 FILE、ifstream、ofstream

在這篇筆記裡頭記錄 FILE、fstream 使用方法及操作

 #include <iostream>
 #include <stdio.h>
 #include <stdlib.h>
 #include <fstream>

 using namespace std;

 int main()
 {
     /*
         r : open for reading
         rb : open for reading in binary mode
         w : open for writing
         wb : open for writing in binary mode
         r+ : support read and write. the file must exit.
         w+ : it like r+ funciton that will recover the file with same file name if file name exit.
     */
     FILE *pFile;

     /* open and create the file */
     pFile = fopen("temp.txt", "w+");
     char buffer[] = "write string test";
     char *rd_buffer;
     /* write the buffer to text file */
     fwrite(buffer, sizeof(char), sizeof(buffer), pFile);
     /* close file */
     fclose(pFile);

     pFile = fopen("temp.txt", "r+");
     /* assign read buffer size */
     rd_buffer = (char*)malloc(sizeof(char)* sizeof(buffer));
     /* read file data to read file */
     fread(rd_buffer, sizeof(char), sizeof(buffer), pFile);
     cout << rd_buffer << endl;
     /* close file */
     fclose(pFile);

     system("pause");
     return ;
 }

在開始進行讀寫之前有一段註解，裡頭主要標示在fopen開檔之後必須填入的參數代表啥意思

    /*
        r : open for reading
        rb : open for reading in binary mode
        w : open for writing
        wb : open for writing in binary mode
        r+ : support read and write. the file must exit.
        w+ : it like r+ funciton that will recover the file with same file name if file name exit.
    */

w/r 就很簡易的只是 : 只能讀 / 只能寫，wb/rb 多個b表示2進制的檔案操作

r+/w+ 多+ : 在操作上就是能讀能寫但是 r+ 有囑意是這個檔案必須存在

在讀檔案的時，有時需求是直接讀一行，利用feof函式去判斷是否讀到最後一行

while (!feof(pFile))
{
    fgets(data, , pFile);
    cout << data;
}

以下是fsteram 檔案基本操作，之後有遇到比較困難的應用在來上頭記錄

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

 using namespace std;

 int main()
 {
     fstream file;

     /* write file operation */
     file.open("temp.txt", ios::out);
     file << "write data to file" << endl;
     file << "fstream write file to test" << endl;
     file << "fstream line 1 test" << endl;
     file << "fstream line 2 test" << endl;
     file << "fstream line 3 test" << endl;
     file << "fstream line 4 test" << endl;
     file << "fstream line 5 test" << endl;
     file << "fstream line 6 test" << endl;
     file << "fstream line 7 test" << endl;
     file << "fstream line 8 test" << endl;
     file.close();

     /* read file operation */
     file.open("temp.txt", ios::in);
     while (!file.eof()){
         char buf[];
         file.getline(buf, );
         cout << buf << endl;
     }
     file.close();

     system("pause");
     return ;
 }