KwCheng's blog

在C++中 , 若我們想要開檔(write file) , 讀檔(read file) , 可以利用ofstream與ifstream來達成我們想要的目的.

ofstream :

int main()

{

ofstream fout("file_B.txt");

fout<<"output string";

fout.close();   // 關閉檔案

return 0;

}

then , the string , "output string" , will be write into the file named file_B.txt.

ifstream : 

#include <fstream> 

using namespace std; 

int main () 

{ 

ifstream ifs ( "test.txt" , ifstream::in ); 

string str;

while (ifs >> str) 

{

cout << str << endl; 

}

ifstream ifs2 ( "test.txt" , ifstream::in ); 

while (getline(ifs2 , str))

{

cout << str << endl;

} 

ifs.close(); 

return 0; 

}

 the instruction , ifs >> str , will read a word one time.

if the content of test.txt is "this is a test file." , the output will be

this

is

a

test

file.

and the instruction , getline(ifs2 , str) , will read a line one time ,

so the outupt will be

this is a test file.

ref : http://finalfrank.pixnet.net/blog/post/22540420-c%2B%2B%E9%96%8B%E8%AE%80%E6%AA%94

ref : http://www.cplusplus.com/reference/iostream/ifstream/ifstream/