C++ Tutorial/File Stream/Text file write — различия между версиями
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Версия 14:21, 25 мая 2010
Содержание
- 1 file output with characters
- 2 file output with strings
- 3 Output a text file character by character
- 4 Output string and decimal in hexadecimal format to a file with ostrstream
- 5 Output to file line by line
- 6 Save string double pair to file
- 7 Use ofstream to write text to a file
- 8 Use put() to write to a file
- 9 Write formatted output to a text file.
- 10 Write to file
file output with characters
#include <fstream>
#include <iostream>
#include <string>
using namespace std;
int main(){
string str = "AAA";
ofstream outfile("TEST.TXT");
for(int j=0; j<str.size(); j++)
outfile.put( str[j] );
cout << "File written\n";
return 0;
}file output with strings
#include <fstream>
using namespace std;
int main(){
ofstream outfile("TEST.TXT");
outfile << "test\n";
outfile << "1\n";
outfile << "2\n";
outfile << "3\n";
return 0;
}Output a text file character by character
#include <iostream>
#include <fstream>
using namespace std;
int main(void){
ifstream in("test.cpp");
if(!in){
cout << "Cannot open file." << endl;
exit (1);
}
in.ignore(10, " ");
char c;
while(in)
{
in.get(c);
cout << c;
}
in.close();
}Output string and decimal in hexadecimal format to a file with ostrstream
#include <strstream>
#include <iostream>
using namespace std;
main()
{
char str[80];
int a = 10;
ostrstream outs(str, sizeof(str));
outs << "Hello there ";
outs << a+44 << hex << " ";
outs.setf(ios::showbase);
outs << 100 << ends;
cout << str;
return 0;
}Output to file line by line
#include <fstream.H>
int main ()
{
ofstream myfile("test.txt");
if (myfile.is_open())
{
myfile << "This outputting a line.\n";
myfile << "this is another line.\n";
myfile.close();
}
return 0;
}Save string double pair to file
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
ofstream out("test.txt"); // output, normal file
if(!out) {
cout << "Cannot open test.txt file.\n";
return 1;
}
out << "R " << 9.9 << endl;
out << "T " << 9.9 << endl;
out << "M " << 4.8 << endl;
out.close();
return 0;
}Use ofstream to write text to a file
#include <iostream>
#include <fstream>
using namespace std;
main(void)
{
char *p = "hello there";
ofstream out("test");
if(!out) {
cout << "Cannot open file";
return 1;
}
while(*p) out.put(*p++);
out.close();
return 0;
}Use put() to write to a file
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
char *p = "hello\n";
ofstream out("test", ios::out | ios::binary);
if(!out) {
cout << "Cannot open file.\n";
return 1;
}
// Write characters until the null-terminator is reached.
while(*p)
out.put(*p++);
out.close();
return 0;
}Write formatted output to a text file.
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
ofstream fout("test.dat");
if(!fout) {
cout << "Cannot open file.\n";
return 1;
}
fout << 10 << " " << -20 << " " << 30.2 << "\n";
fout << "This is a test.";
fout.close();
if(!fout.good()) {
cout << "A file error occurred.";
return 1;
}
}Write to file
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
ofstream out("test.txt");
if(!out) {
cout << "Cannot open file.\n";
return 1;
}
out << 10 << " " << 123.23 << "\n";
out << "This is a text.";
out.close();
return 0;
}