extract filename from filepath, problem handling strings

**larne** · 08-29-2008

Hello
I am trying to use a method that extracts the filename out of a filepath but I cant seem to make it work. The code worked ok within another function, but now when I try to separate it into its own function it doesnt work anymore. =/
This is my function

Code:

#include "gbs.h"

char * extract_filename(char *str){
	
	int ch = '\\', result, len;
	char  *pdest, line[250], *inpfile = {NULL};

	// Search backwards for last backslash in filepath /
	inpfile = (char *)malloc(200*sizeof(char));
	pdest = strrchr(str, ch);	result = pdest - str + 1;
	
	// if backslash not found in filepath
	if(pdest == NULL ){
		printf( "Result:\t%c not found\n" );
	}
	
	// extract filename from file path /
	len = strlen(str) - result - 1;
	strncpy(inpfile, &line[result], len);
	inpfile[len] = NULL;
	return inpfile;
}

The function is declared in the header gbs.h. I try to call the function from another function like this. I omitted most of the code to not make the post shorter.

Code:

void anotherfunction()
{
        char *filename, filepath[200];

        //some code

	fscanf(fp,"%s",filepath);
	printf("%s\n",filepath);
        
	filename= extract_filename(filepath);
        printf("%s\n",filename);
}

The printf("%s\n",filepath); is printed OK, but the output from printf("%s\n",filename); is this: ╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠╠kkkk
I am new to this and I would be very thankful for any ideas!

**matsp** · 08-29-2008

What is the content of "line"? You probably want to remove that variable, and use "str" instead.

Also, you are mallocing unnecessarily large space - seeing as you calculate len of the string [although it's one off].

And you could simplify everything by using pdest in itself - something like this:

Code:

char * extract_filename(char *str)
{
    int     ch = '\\';
    size_t  len;
    char   *pdest;
    char   *inpfile = NULL;

    // Search backwards for last backslash in filepath 
    pdest = strrchr(str, ch);
	
    // if backslash not found in filepath
    if(pdest == NULL )
    {
	printf( "Result:\t%c not found\n", ch );
	pdest = str;  // The whole name is a file in current path? 
    }
    else 
    {
	pdest++; // Skip the backslash itself.
    }
	
    // extract filename from file path
    len = strlen(pdest);
    inpfile = malloc(len+1);  // Make space for the zero.
    strncpy(inpfile, pdest, len+1);  // Copy including zero. 
    return inpfile;
}

Please, before you copy and paste my answer, understand what went wrong in your code and try to fix it. That will teach you a lot more than copy'n'paste-skills can.

--
Mats

**larne** · 08-29-2008

Brilliant help =D
Thank you very much!

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