Character arrays can be used like files

NOTE : -

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32. Character arrays can be used like files

Generally speaking, it is possible to do on character arrays the same operations as on files. This is very useful to convert data or manage memory arrays.

Here is a program that writes inside a character array:

using namespace std;
#include 
#include 
#include 
#include 

int main ()
{
  char a[1024];
  ostrstream b(a, 1024);

  b.seekp(0);                           // Start from first char.
  b << "2 + 2 = " << 2 + 2 << ends;     // ( ends, not endl )
                                        // ends is simply the
                                        // null character   '\0'
  cout << a << endl;

  double v = 2;

  strcpy (a, "A sinus: ");

  b.seekp(strlen (a));
  b << "sin (" << v << ") = " << sin(v) << ends;

  cout << a << endl;

  return 0;
}

Output

2 + 2 = 4 A sinus: sin (2) = 0.909297

A program that reads from a character string:

using namespace std;
#include 
#include 
#include 

int main ()
{
  char a[1024];
  istrstream b(a, 1024);

  strcpy (a, "45.656");

  double k, p;

  b.seekg(0);                       // Start from first character.
  b >> k;

  k = k + 1;

  cout << k << endl;

  strcpy (a, "444.23 56.89");

  b.seekg(0);
  b >> k >> p;

  cout << k << ", " << p + 1 << endl;

  return 0;
}

Output

46.656 444.23, 57.89

BIBILOGRAPHY / REFERENCE : - http://www.4p8.com/eric.brasseur/cppcen.html