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Arg Class Template Reference

Read and extract commandline parameters from argc/argv. More...

#include <Pt/Arg.h>

List of all members.

Public Member Functions
	Arg (const T &def=T())
	Default constructor. Initializes value.
	Arg (int &argc, char *argv[], char ch, const T &def=T())
	extract parameter.
	Arg (int &argc, char *argv[], const char *str, const T &def=T())
	definition of long options.
	Arg (int &argc, char *argv[])
bool	set (int &argc, char *argv[], char ch)
	extract parameter.
bool	set (int &argc, char *argv[], const char *str)
	definition of long options.
bool	set (int &argc, char *argv[])
	Reads next parameter and removes it.
const T &	getValue () const
	returns the value.
	operator T () const
	returns the value.
bool	isSet () const
	returns true, if the option was found and the default was not used.

---

Detailed Description

template<typename T>
class Pt::Arg< T >

Programs usually need some parameters. Usually they start with a '-' followed by a single character and optionally a value. Arg<T> extracts these and other parametes.

This default class processes paramters with a value, which defines a input-extractor-operator operator>> (istream&, T&).

Options are removed from the option-list, so programs can easily check after all options are extracted, if there are parameters left.

example:

          int main(int argc, char* argv[])
          {
            cxxtools::Arg<int> option_n(argc, argv, 'n', 0);
            std::cout << "value for -n: " << option_n << endl;
          }

---

Constructor & Destructor Documentation

Arg

(

const T &

def = T()

)

Parameters:

def

initial value

Arg	(	int &	argc,
		char *	argv[],
		char	ch,
		const T &	def = T()
	)

Parameters:

	argc	1. parameter of main
	argv	2. of main
	ch	optioncharacter
	def	default-value

example:

                Arg<unsigned> offset(argc, argv, 'o', 0);
                unsigned value = offset.getValue();

Arg	(	int &	argc,
		char *	argv[],
		const char *	str,
		const T &	def = T()
	)

GNU defines long options starting with "--". This (and more) is supported here. Instead of giving a single option-character, you specify a string.

example:

                 Arg<int> option_number(argc, argv, "--number", 0);
                 std::cout << "number =" << option_number.getValue() << std::endl;

---

Member Function Documentation

bool set	(	int &	argc,
		char *	argv[],
		char	ch
	)

Parameters:

	argc	1. parameter of main
	argv	2. of main
	ch	optioncharacter

example:

                Arg<unsigned> offset;
                offset.set(argc, argv, 'o');
                unsigned value = offset.getValue();

bool set	(	int &	argc,
		char *	argv[],
		const char *	str
	)

GNU defines long options starting with "--". This (and more) is supported here. Instead of giving a single option-character, you specify a string.

example:

                  Arg<int> option_number;
                  number.set(argc, argv, "--number");
                  std::cout << "number =" << option_number.getValue() << std::endl;

operator T

(

)

const

Instead of calling getValue() the argument can be converted implicitly.

example:

                void print(int i)
                { std::cout << i << std::endl; }

                int main(int argc, char* argv[])
                {
                  cxxtools::Arg<int> value(argc, argv, 'v', 0);
                  print(value);   // pass argument as a int to the function
                }

Copyright © 2003-2007 The Pt Development Team

Pt 1.0