C++ Tutorial/File Stream/file open mode
Версия от 14:21, 25 мая 2010; (обсуждение)
Содержание
Appending to the End of a File
#include <fstream>
#include <iostream>
using namespace std;
int main()
{
char buffer[255];
ifstream fin("text.txt");
if (fin)
{
char ch;
while (fin.get(ch))
cout << ch;
}
fin.close();
cout << "in append mode...\n";
ofstream fout("text.txt",ios::app);
if (!fout)
{
cout << "Unable to open for appending.\n";
return(1);
}
cout << "\nEnter text for the file: ";
cin.ignore(1,"\n");
cin.getline(buffer,255);
fout << buffer << "\n";
fout.close();
fin.open("text.txt");
if (!fin)
{
cout << "Unable to open for reading.\n";
return(1);
}
char ch;
while (fin.get(ch))
cout << ch;
fin.close();
return 0;
}Open a file as binary file and get its size
#include <fstream>
#include <iostream>
using namespace std;
int main ()
{
long start,end;
ifstream myfile ("test.txt", ios::in|ios::binary);
start = myfile.tellg();
myfile.seekg (0, ios::end);
end = myfile.tellg();
myfile.close();
cout << "size of " << "test.txt";
cout << " is " << (end-start) << " bytes.\n";
return 0;
}size of test.txt is 25 bytes.
Open a file for appending and append
#include <fstream>
#include <iostream>
using namespace std;
int main ()
{
char buffer[256];
fstream myfile;
//open for appending and append
myfile.open("test.txt",ios::app);
myfile << " Hey this is another line \n";
myfile.close();
return 0;
}Open a file for input and read in its content
#include <fstream>
#include <iostream>
using namespace std;
int main ()
{
char buffer[256];
fstream myfile;
// open it for input and read in
myfile.open("test.txt",ios::in);
myfile.getline(buffer,100);
cout << "The file contains " << buffer << "\n";
myfile.close();
return 0;
}The file contains This outputting a line.
Opening files for read and write.
#include <fstream>
#include <iostream>
using namespace std;
int main()
{
char buffer[255];
ofstream fout("text.txt");
fout << "test\n";
cout << "Enter text for the file: ";
cin.ignore(1,"\n");
cin.getline(buffer,255);
fout << buffer << "\n";
fout.close();
ifstream fin("text.txt");
char ch;
while (fin.get(ch))
cout << ch;
fin.close();
return 0;
}Opening text Files for Read and Write
#include <fstream>
#include <iostream>
using namespace std;
int main()
{
char buffer[255];
ofstream fout("text.txt");
fout << "this is a test\n";
cout << "Enter text for the file: ";
cin.ignore(1,"\n");
cin.getline(buffer,255);
fout << buffer << "\n";
fout.close();
ifstream fin("text.txt");
cout << "Here"s the contents of the file:\n";
char ch;
while (fin.get(ch))
cout << ch;
fin.close();
return 0;
}