Hi All,
This seemingly simple thing is causing me alot of trouble.  Can someone show me
how I can convert an array of char[][] to a char**.

Here is the pseudo code...

void runWithArgs( char[][] args ) {
char** execArgs;

// convert args to execArgs

execv( toStringz( "myprog" ), execArgs );

}


thanks,
Glen

On Fri, 21 Apr 2006 02:07:17 +0000 (UTC), glen wrote:

> Hi All,
> This seemingly simple thing is causing me alot of trouble.  Can someone show me
> how I can convert an array of char[][] to a char**.
> 
> Here is the pseudo code...
> 
> void runWithArgs( char[][] args ) {
> char** execArgs;
> 
> // convert args to execArgs
> 
> execv( toStringz( "myprog" ), execArgs );
> 
> }
> 

On the assumption that 'char**' points to an array of 'char*' and that array is terminated with a null pointer, then this might be what you are looking for ...

-----------------
import std.string;
char** toArgList(char[][] pOrig)
{
    char*[] lTemp;
    lTemp.length = pOrig.length + 1;
    foreach(int i, char[] pc; pOrig)
    {
        lTemp[i] = toStringz(pc);
    }
    lTemp[$-1] = null;

    return lTemp.ptr;
}

void main(char[][] pArgs)
{
    char** lOldStyle;

    lOldStyle = toArgList(pArgs);

    // Use the counted method of accessing them.
    for(int i = 0; i < pArgs.length; i++)
    {
        printf("%d '%s'\n", i, *(lOldStyle+i));
    }

    // Use the terminating null method of accessing them.
    int j;
    char* cp;
    while(true)
    {
        cp = *(lOldStyle+j);
        if (cp == null)
            break;
        printf("%d '%s'\n", j, cp);
        j++;
    }

}
-----------------

-- 
Derek
(skype: derek.j.parnell)
Melbourne, Australia
"Down with mediocracy!"
21/04/2006 1:07:07 PM

In article <e29eol$5sa$1@digitaldaemon.com>, glen says...
>
>Hi All,
>This seemingly simple thing is causing me alot of trouble.  Can someone show me
>how I can convert an array of char[][] to a char**.
>
>Here is the pseudo code...
>
>void runWithArgs( char[][] args ) {
>char** execArgs;
>
>// convert args to execArgs
>
>execv( toStringz( "myprog" ), execArgs );
>
>}
>
>
>thanks,
>Glen
>
>

this is quick and dirty but should work

char[][] src; // what to convert

alias char* cahr_p; // alias b/c I can't remember the syntax for a array of ptrs

char_p[] res = new char_p[src.length+1];

foreach(int i, char[] st, src)
res[i] = st.ptr;

res[$-1] = null;

// now use

res.ptr

[snip]
> 
> alias char* cahr_p; // alias b/c I can't remember the syntax for a array of ptrs
> 

Read it right-to-left.

char*[] <-- array of pointers to chars

If that doesn't help, you can always make an alias, and *then* expand it.

alias char* char_p;

char_p[]
    --> (char*)[]
    -->   char*[]

At least, that's how I work it out :)

	-- Daniel

-- 

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