Console (command line)

[JasonLpz]

ok i know some c++ cuz of you people out her thanks now i want to know about the command line arguments . Do they have to do with

int main (int nArgs, char* pszArgs[])

if i do this

#include <stdio.h>
#include <iostream.h>
 
 
int main (int nVal, int nVal2, char* pszArgs[])
{
 
int nVal3 = nVal + nVal2;
cout << "The total is: " << nVal3;
 
 
return 0;
}

Will it work? Like how would i enter the command line arg?
like
Add.exe 3, 4 is incorrect but whats the right way

[twanvl]

No, the command line arguments don't work like that. The arguments are passed as an array of char*s, the first argument of main is the number of arguments in the array, the second is the array itself:

#include <iostream>
#include <cstdlib>
using namespace std;

int main(int argc, char** argv)
{
    if (argc!=3) {
        cerr << "You must pass two arguments" << endl;
    }
    int val1 = atoi(argv[1]);
    int val2 = atoi(argv[1]);
    cout << val1 << " + " << val2 << " = " << (val1+val2) << endl;
    return 0;
}

Note that the first argument of argv is always the name of the program as it is called (therefore argc will be one more then the actual number of arguments)

[JasonLpz]

how do i enter the 2 args now?

[JasonLpz]

Oops theres your problem thanks its great now

int val1 = atoi(argv[1]);
    int val2 = atoi(argv[2]);

[JasonLpz]

ok great so far so good. Now i have 1 problem i made this program with the info u gave me. Now i get this error not when i compile but when i run this without any arguments. how can i catch this error and stop it like if they dont type any arguments then show the

if (sVal == 0) {
        cout << "You must select a program to run. Press number to run program.\n";
        cout << "\n1 = Adding Application";
        cout << "\n2 = Subtract Application";
        cout << "\n3 = Multiply Application";
        cout << "\n4 = Divide Application\n\n\n";
 }

#include <iostream>
#include <cstdlib>
using namespace std;
 
int main(int argc, char** argv)
{
    
    int sVal = atoi(argv[1]);
    
    if (argc!=3) {
        cerr << "For A list or programs press 0.\n\n"<< endl;
    }
        
 
 
    if (sVal == 0) {
      cout << "||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||\n";
          cout << "||You must select a program to run. Press number to run program.||\n";
      cout << "||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||";
        cout << "\n||1 = Adding Application                                        ||";
    cout << "\n||2 = Subtract Application                                      ||";
    cout << "\n||3 = Multiply Application                                      ||";
    cout << "\n||4 = Divide Application                                        ||\n";
      cout << "||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||\n\n\n"
 }
 
if (sVal == 1)
    {
int a1;
int a2;
int a3;
 
cout << "Enter numbers below to add\n";
    
cout << "1:";
cin >> a1;
        
cout << "2: ";
cin >> a2;
 
a3 = a1 + a2;
 
cout << "\n\n The Sum is: " << a1 << " + " << a2 << " = " << a3;
 
    }
 
if (sVal == 2)
    {
int a1;
int a2;
int a3;
 
cout << "Enter numbers below to subtract\n";
 
cout << "1:";
cin >> a1;
        
cout << "2: ";
cin >> a2;
 
a3 = a1 - a2;
 
cout << "\n\n The Subtracted sum is: " << a1 << " - " << a2 << " = " << a3;
 
    }
 
if (sVal == 3)
    {
int a1;
int a2;
int a3;
 
cout << "Enter numbers below to multiply\n";
        
cout << "1:";
cin >> a1;
        
cout << "2: ";
cin >> a2;
 
a3 = a1 * a2;
 
cout << "\n\n The Multiplied sum is: " << a1 << " x " << a2 << " = " << a3;
 
    }
if (sVal == 4)
    {
int a1;
int a2;
int a3;
 
cout << "Enter numbers below to divide\n";
        
cout << "1:";
cin >> a1;
        
cout << "2: ";
cin >> a2;
 
a3 = a1 / a2;
 
cout << "\n\n The Divided sum is: " << a1 << " / " << a2 << " = " << a3;
 
    }
    return 0;
}

[JasonLpz]

oh yeah in VB there is a easy to use SELECT CASE is there something like this in c++ (there must be ) Can someone tell me something about that plz thank you all

[CornedBee]

There's a switch in C++ that does the same as select in VB. It can't handle strings though.

As for this:
int sVal = atoi(argv[1]);
Don't access any command line arguments without having checked that there really is something! If the user starts your app without arguments then you'll probably end up with an access violation.

[JasonLpz]

ok thanks got it

int main(int argc, char** argv)
{
cout << "||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||\n";
cout << "||You must select a program to run. Press number to run program.||\n";
cout << "||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||";
cout << "\n||0 = This list                                                 ||";
cout << "\n||1 = Adding Application                                        ||";
cout << "\n||2 = Subtract Application                                      ||";
cout << "\n||3 = Multiply Application                                      ||";
cout << "\n||4 = Divide Application                                        ||\n";
cout <<  "||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||\n\n\n";
    
int sVal;
if (argc!=3) {
cerr << ""<< endl;
}
 
    
if (argc!=1){
sVal = atoi(argv[1]);
}

[JasonLpz]

another question. I noticed my programs wil close if i just double click them is there a way to change this?

[CornedBee]

I guess they open, notice that there are insufficient arguments and thus end. The console window is not kep open.

To make up for that you can either start the app from a console window or add a line of code that keeps the window open (like cin.ignore(1); )