C++ Tutorial/File Stream/ostrstream

Check how many characters are stored in ostrstream

<source lang="cpp">#include <strstream>

1. include <iostream>

using namespace std; main() {

 char str[80];   
    
 ostrstream outs(str, sizeof(str));   
    
 outs << "Hello ";   
 outs << 34 << " " << 1234.23;   
 outs << ends;  
    
 cout << outs.pcount(); // display how many chars in outs   
    
 cout << " " << str;   
    
 return 0;   

}</source>

Display how many chars in ostrstream

<source lang="cpp">#include <strstream>

1. include <iostream>

using namespace std; int main() {

 char str[80];
 ostrstream outs(str, sizeof(str));
 outs << "abcdefg ";
 outs << 27 << " "  << 890.23;
 outs << ends;  // null terminate
 cout << outs.pcount(); // display how many chars in outs
 cout << " " << str;
 return 0;

}</source>

18 abcdefg 27 890.23"

Freeze dynamic buffer and return pointer to it

<source lang="cpp">#include <strstream>

1. include <iostream>

using namespace std; int main() {

 char *p;
 ostrstream outs;
 outs << "AAAAAAAAAAAAAAAAAAAA";
 outs << -10 << hex << " ";
 outs.setf(ios::showbase);
 outs << 100 << ends;
 p = outs.str();
 cout << p;
 return 0;

}</source>

AAAAAAAAAAAAAAAAAAAA-10 0x64"

Make ostringstream work with decimal, hexadecimal value, floating value, bitset

<source lang="cpp">/* The following code example is taken from the book

* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/

1. include <iostream>
2. include <sstream>
3. include <bitset>

using namespace std; int main() {

   ostringstream os;
   // decimal and hexadecimal value
   os << "dec: " << 15 << hex << " hex: " << 15 << endl;
   cout << os.str() << endl;
   // append floating value and bitset
   bitset<15> b(5789);
   os << "float: " << 4.67 << " bitset: " << b << endl;
   // overwrite with octal value
   os.seekp(0);
   os << "oct: " << oct << 15;
   cout << os.str() << endl;

}</source>

dec: 15 hex: f
oct: 17 hex: f
float: 4.67 bitset: 001011010011101

ostrstream with format

<source lang="cpp">#include <strstream>

1. include <iostream>

using namespace std; int main() {

 char str[80];
 ostrstream outs(str, sizeof(str));
 outs << "AAAAAAAAAAAAAAAA. ";
 outs << 1024 << hex << " ";
 outs.setf(ios::showbase);
 outs << 100 << " " << 99.789 << ends;
 cout << str;  // display string on console
 return 0;

}</source>

AAAAAAAAAAAAAAAA. 1024 0x64 99.789"

Output of several data types to an ostringstream object: double, int and address of int

<source lang="cpp">#include <iostream> using std::cout; using std::endl;

1. include <string>

using std::string;

1. include <sstream>

using std::ostringstream; int main() {

  ostringstream outputString;
  string string1( "string " );
  double double1 = 123.4567;
  int integer = 22;
  outputString << string1 << double1  << integer << &integer;
  // call str to obtain string contents of the ostringstream
  cout << "outputString contains:\n" << outputString.str();
  return 0;

}</source>

outputString contains:
string 123.457220x22fe74"

Save string with ostringstream

<source lang="cpp">#include <iostream>

1. include <sstream>

using namespace std; int main(int argc, char** argv) {

 cout << "Enter tokens. Control-D (Unix) or Control-Z (Windows) to end." << endl;
 ostringstream outStream;
 while (cin) {
   string nextToken;
   cout << "Next token: ";
   cin >> nextToken;
   if (nextToken == "done") break;
   outStream << nextToken << "\t";        
 }
 cout << "The end result is: " << outStream.str();

}</source>