Re: [Dev-C++] Using Command Line to Execute program

[Jason H. <jas...@bt...>]

Ooops, I sent this directly to Mr. Chuong rather than to the Dev-C++ mailing
list. It would be nicer if the reply address with mailing list items was
automatically back to the mailing list. Here's what I said:

I have corrected a few errors that I can see, but I've not tested the
outcome so I'll leave that to you. Note that passing as an array and passing
as a pointer equate to the same thing.

#include  <iostream.h>
#include  <stdlib.h>
#include <stdio.h>

//--------------------------------------------------------------------------
--

----
// array passed as pointer

float  sum_array( float *A, int len )
{
    float s = 0;
    for( int i = 0; i < len; ++i )
    s += A[i];
    return s;
}

// array passed as array of unspecified length

float  average_array( float A[], int len )
{
    return  sum_array( A, len )/len;
}

//--------------------------------------------------------------------------
--

----
void  main( int argc, char **argv )
{
    if( argc != 2 ) /* there will always be at least 1 in argc as the name
of the executable counts as an argument */
    {
        cerr << "Usage: " << argv[0] << " number" << endl;
        cerr <<"int argc: "<<argc;
        getchar();
        exit(0);
    }

    int  n = atoi( argv[1] ); /* you don't check that a valid result was
given, but I assume that you will be giving correct commands */

    //float  H[n];
/* this is illegal in all but the latest C standard (C99), you cannot
allocate an array with a variable size. You should use dynamic allocation,
as follows */

    float *H = new float[n]; /* I'm not absolutely sure of syntax off the
top of my head, so check it works.*/

    for( int i = 1; i <= n; ++i )
    H[i-1] = 1.0/static_cast<float>(i); /* this is a better way of making
the result float, i.e. use a float literal and cast the integer into a
float, although it would probably have been an implicit cast anyway */

    cout << "harmonic number " << n << ":   " << sum_array( H, n ) << endl;
    cout << "average 1/i up to " << n << ": " << average_array( H, n ) <<
endl;

    system("PAUSE");
    delete[] H; // don't forget to delete array when finished with it
    exit(0);
}

I hope those little pointers help you. I'll leave it to you to debug what I
have written. I don't think I have made any mistakes (maybe some typing
errors) but I didn't have time to check.

Jason.


----- Original Message -----
From: <Cuo...@ao...>
To: <dev...@li...>
Sent: Thursday, November 15, 2001 6:41 AM
Subject: [Dev-C++] Using Command Line to Execute program


> Please show me step-by-step how to use DevC++ to run a program through
> Command Line method fpr the following program. Thank you!!!!!!!!!!!!!!
>
>
> #include  <iostream.h>
> #include  <stdlib.h>
> #include <stdio.h>
>
>
//--------------------------------------------------------------------------
--
>
> ----
> // array passed as pointer
>
> float  sum_array( float *A, int len )
> {
>     float s = 0;
>     for( int i = 0; i < len; ++i )
>     s += A[i];
>     return s;
> }
>
> // array passed as array of unspecified length
>
> float  average_array( float A[], int len )
> {
>     return  sum_array( A, len )/len;
> }
>
>
//--------------------------------------------------------------------------
--
>
> ----
> void  main( int argc, char **argv )
> {
>     if( argc != 1 )
>     {
>         cerr << "Usage: " << argv[0] << " number" << endl;
>         cerr <<"int argc: "<<argc;
>         getchar();
>         exit(0);
>     }
>
>     int  n = atoi( argv[1] );
>
>     float  H[n];
>
>     for( int i = 1; i <= n; ++i )
>     H[i-1] = 1/float(i);
>
>     cout << "harmonic number " << n << ":   " << sum_array( H, n ) <<
endl;
>     cout << "average 1/i up to " << n << ": " << average_array( H, n ) <<
> endl;
>
>     exit(0);
> }
>
> //--------------------------------
> ------------------------------------------------
>
>
>
>
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