Thread: Managing strings, renaming problems

Hi, I'd like to make a program which does this renaming work:

example.txt -> example(copy).txt

Also, I'd like it to support any number of '.' into the file name, like:

example.2011.txt -> example.2011(copy).txt

I've tried using string.h functions... and I didn't think it could be that hard.

I don't need help about the file managing (fopen, rename, etc). I just need help finding the correct position where to add the "(copy)".

I've been working on it for some hours... then I decided to ask here because probably the code became too complex for the simple work.

Here it is:

Code:

#include <stdio.h>
#include <string.h>

int main(int argc, char *argv[])
{
	char **ppc; // to visit **argv
	char *est; // where to attach strings' extension
	char *result; // resultant filename
	int dim; // string length
	int dim2; // 2nd string length
	int i; // this serves like an index
	int i2; // used to find filename's first part, then to copy the extension part
	int i3;

    if(argc > 1)
    {
    	ppc = argv + 1;
    	for(i = 1; i < argc; ++i)
    	{
    		printf("%s renamed to ", *ppc);
			dim = strlen(*ppc);
			est = strrchr(*ppc, '.');
			i2 = est - *ppc;
			printf("\ni2 = %d (number of letters before the last '.')\n", i2);
			result = strncpy(result, *ppc, i2);
			printf("\nresult: %s\n", result);
			i3 = i2 = dim - i2;
			printf("\ni2: %d\n", i2);
			while(i2-- > 0)
			{
				printf("%c", *est++);
				//est++;
				//*est = *est;
				//*(++est) = *(est+1);
			}
			//est = est - i2
			*(est) = '\0';
			est = est - i3;
			printf("\nextension: %s\n", est);
			dim2 = strlen(est);
			//result = strncpy(result, *ppc, dim - dim2);
			result = strcat(result, "(copy)");
			result = strcat(result, est);
			printf("%s\n", result);
    	}
	}

    return 0;
}

If you are on *nix, you can use the terminal and try "./binaryname example.txt" and it will work. But when I tried "./binaryname example.2011.txt" it printed some weird characterhs through the name.

Where do I make errors?
Thank you

Code:

	char *result; // resultant filename

If you are going to use result as though it pointed somewhere useful (such as, say, "result = strncpy(result, *ppc, i2);"), then you should make sure that it does, in fact, point somewhere useful.

Originally Posted by kr0n1x

edit: maybe I got it. When I use strncpy, does it allocate the space and assign it to result... or not?? Is this the problem?

strncpy does no space allocating at all.

Originally Posted by tabstop

strncpy does no space allocating at all.

Yay I got it

#include malloc.h

then, right before the strncpy instruction, I put:
result = malloc(i2);

Now it seems to work thanks! I will complete it for multiple files.

Rhetorical question: Is there a better way to do this job? How?

I'm curious to see how simple this could be... and learn more

Originally Posted by laserlight

No, that should be #include <stdlib.h>

Oh... at the university my professors taught me wrong.
I didn't know that it contained malloc too... I'm reading on wikipedia right now.