Summary of C ++ read/write file instances (stringtoken is read in units and char is read in units)

 

1. Read all strings separated by spaces in the specified file.

 

# Include <fstream>

 

Ifstream indata; // For the file

Indata. Clear ();

String filename;
Filename = "primes.txt ";

Indata. Open (filename. c_str ());
String temp_word;

// You can also directly read the integer data int temp_word here;
// Indata> temp_word;

 

While (indata. EOF ())

// If the file contains a line break, you need to use while (indata. Good () to determine whether it is at the end of the file.
{
Indata> temp_word;
}

 

Note: If you use # include <fstream>, you cannot use ifstream,

You can try:

# Include "stdafx. H"
# Include <cstdlib>

# Include <iostream>
# Include <fstream>
# Include <string>
Using namespace STD;

 

2. Read all characters in the specified file, including Spaces

 

# Include <fstream>

 

Ifstream indata;

String filename;

String temp_word;

 

Filename = "aaa.txt ";

Indata. Open (filename. c_str ());

 

Indata. seekg (0, IOS: End );

Streampos PS = indata. tellg ();
// Cout <"file size:" <ps <Endl;

Indata. Close ();

 

Const char * filenamechar = filename. c_str ();

Ifstream myinf (filenamechar );
Int size = Ps;
// Char STR [1000000]; //
Char * STR = new char [size + 100];

// Read File
Myinf. Read (STR, PS );
Myinf. Close (); // close file

 

For (INT I = 0; I <ps; I ++)
{
// Test what has been read
// Cout <STR [I];

// Store character

If (STR [I]! =-52) // if not null
{
Temp_word = STR [I];
}
}

 

3. Write the specified content to the file

Format and write

 

# Include <iostream>
Using namespace STD;
# Include <string>
# Include <fstream>
// # Include <cstdlib>
# Include <iomanip>

 

Ofstream F1;
String fileout = "tabular.txt ";
F1.open (fileout. c_str ());
If (! F1) return;

 

F1 <setiosflags (IOs: right );
F1 <SETW (15) <"employee ID number ";
F1 <SETW (20) <"name ";
F1 <SETW (15) <"gross pay ";
F1 <SETW (15) <"tax ";
F1 <SETW (15) <"net pay" <Endl;

F1.close ();

 

F1 <SETW (15) <setprecision (2) <grosspay;

You can use setprecision to set the reserved digits of a floating point.

 

Unformatted write

// String nowdata = "employee ID number name gross pay tax net pay ";

/*
Int size = nowdata. Size ();
Char * Ch = new char [1];
* Ch = * (nowdata. c_str ());
// Char * buffer;
For (INT I = 0; I <size; I ++)
{
* Ch = * (nowdata. substr (I, 1). c_str ());
// Char * buffer;
F1.write (CH, 1 );
}
*/
F1.close ();