Drag and drop onto executable

This is a discussion on Drag and drop onto executable within the C Programming forums, part of the General Programming Boards category; All I want is to automate a program (which requires a lot of command line input to work) via a ...

  1. #1
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    Drag and drop onto executable

    All I want is to automate a program (which requires a lot of command line input to work) via a drag and drop interface. My first stop was batch programming, but I quickly found out that it's not even really possible to grab the extension of a file in there (with any straightforwardness).

    So, I turn to my old standard, a c program. I think I know how to grab an extension in c, but I have no idea how to grab a file name/path from a drag and drop execution. Where would I go to start learning this?

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    Guest Sebastiani's Avatar
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    Code:
    #include <stdlib.h>
    #include <stdio.h>
    
    int main( int argc, char** argv, char** envp )
    {
    	if( argc > 1 )
    		puts( "- Command Line -" );
    	while( *( ++argv ) )
    		puts( *argv );
    	puts( "- Environment Variables -" );
    	while( *envp )
    		puts( *envp++ );
    	return 0;
    }

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    OK, I think I understand the argc argv part. So, if I started a program like this:

    Code:
    #include <stdlib.h>
    #include <stdio.h>
    
    int main(int argc, char** argv)
    {
    	for (int i = 0; i < argc; i++)
    	{
    how would I then pull the extension out? Is there some scan function I can use to find the index of the period and then pull everything else out after it and put it into an ext var?

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    Guest Sebastiani's Avatar
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    Quote Originally Posted by Molokai View Post
    OK, I think I understand the argc argv part. So, if I started a program like this:

    Code:
    #include <stdlib.h>
    #include <stdio.h>
    
    int main(int argc, char** argv)
    {
        for (int i = 0; i < argc; i++)
        {
    how would I then pull the extension out? Is there some scan function I can use to find the index of the period and then pull everything else out after it and put it into an ext var?
    First of all, the first element of the command line parameter array is the name of the program, so you definitely want to skip that. As to your question, probably the easiest way would be to use the 'strrchr' function (included via 'string.h'), which finds the last occurence of a particular character in a string. Search for the '.' and, if found, everything after that will be the actual extension, naturally.

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    Ah, OK, so I start with i = 1 and run through the argv[]. Is argv really in char format, and does that mean that it would be in something like argv[argc][] format, or is it really a string array? Or is there a difference?

  6. #6
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    Quote Originally Posted by Molokai View Post
    Ah, OK, so I start with i = 1 and run through the argv[]. Is argv really in char format, and does that mean that it would be in something like argv[argc][] format, or is it really a string array? Or is there a difference?
    I have no idea what this question is asking. But: argv is what it says it is, a char ** (which equals for our purposes in this case a char *[]). So argv[0] is a char *, argv[1] is a char *, argv[2] is a char *, ....

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    Guest Sebastiani's Avatar
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    Quote Originally Posted by Molokai View Post
    Ah, OK, so I start with i = 1 and run through the argv[]. Is argv really in char format, and does that mean that it would be in something like argv[argc][] format, or is it really a string array? Or is there a difference?
    It's as if the calling code had passed your program the following array:

    Code:
    char* argv[ ] = 
    {
        "my_prog.exe", 
        "-foo", 
        "bar.txt", 
        "baz.cpp", 
        "qux.dat", 
    /*
        Null terminated, so that the 
        user knows where to stop
    */
        0    
    };

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    I don't know if this is heading in the right direction, but this is how you work with file extensions, in a bat file.

    This bat file, will type out all files with the txt file extension, in the current directory.
    Code:
    echo off
    for %%1 in (*.txt) do type %%1
    pause
    Bat files were made for this kind of work, I believe. I'm *very* unclear why you think that bat files are not "straightforward".

    There are extensive tutorials for bat files, on the web.

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