C++ Tutorial/Development/command line arguments — различия между версиями

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м (1 версия: Импорт контента...)
 
(нет различий)

Текущая версия на 10:28, 25 мая 2010

Display command-line arguments

#include <iostream> 
using namespace std; 
 
int main(int argc, char *argv[]) 
{ 
 
  for(int i = 0; i < argc; i++) { 
    cout << argv[i] << "\n"; 
  } 
 
  return 0; 
}
main

Sum the two numeric command line arguments

#include <iostream> 
#include <cstdlib> 
using namespace std; 
 
int main(int argc, char *argv[]) 
{ 
  double a, b; 
 
  if(argc!=3) { 
    cout << "Usage: main num num\n"; 
    return 1; 
  } 
 
  a = atof(argv[1]); // convert first command-line arg 
  b = atof(argv[2]); // convert second comnand-line arg 
 
  cout << a + b; 
 
  return 0; 
}
Usage: main num num

Using command-line arguments for copying files

#include <iostream>
using std::cout;
using std::endl;
using std::ios;
#include <fstream>
using std::ifstream;
using std::ofstream;
int main( int argc, char *argv[] )
{
   // check number of command-line arguments
   if ( argc != 3 )
      cout << "Usage: copyFile infile_name outfile_name" << endl;
   else
   {
      ifstream inFile( argv[ 1 ], ios::in );
      if ( !inFile )
      {
         cout << argv[ 1 ] << " could not be opened" << endl;
         return -1;
      }
      ofstream outFile( argv[ 2 ], ios::out );
      if ( !outFile )
      {
         cout << argv[ 2 ] << " could not be opened" << endl;
         inFile.close();
         return -2;
      }
      char c = inFile.get();
      while ( inFile )
      {
         outFile.put( c );  
         c = inFile.get();
      }
   }
   return 0;
}
Usage: copyFile infile_name outfile_name