C + + Learning Note 16:linux System programming Fundamentals 1

Parameter list

Linux Command line specification

• Short parameter: Starts with a single cross, followed by a single character, for example: ls-h
• Long parameter: begins with a double-cross, followed by a string, for example: LS--help

Program Access parameter list method:

• Parameters argc and argv of the main function
• The program accepts the input parameters of the command line and interprets the

Writing programs, outputting command-line arguments

#include <iostream>using namespacestd;intMainintargcChar*argv[]) {cout<<"The program name is:"<< argv[0] <<" ."<<Endl; if(Argc >1) {cout<<" with"<< ARGC-1<<"args as follows:"<<Endl;  for(inti =0; i < argc; i++) {cout<< Argv[i] <<Endl; }    }    Else{cout<<" with"<< ARGC-1<<"arguments."<<Endl; }    return 0;}

Parameter list:

Definition of an option array

struct type option: The system is defined and can be used directly

Header file: getopt.h

struct option

{

Option long name

const char *name;

Option has additional parameters: 0, none, 1, available; 2, optional;

int has_arg;

Point to Integer, which holds the value of Val, set to 0

int *flag;

Option short name

int Val;

};

function Getopt_long ()

-V/--verbose: output complex information

C + + Learning Note 16:linux System programming Fundamentals 1