Rename C Program - Trouble getting values into rename function

I'm working on a C program to batch rename files in reverse order. To make it easy I'm hard coding the file names - using a loop - instead of using C to read the directory. My problem is getting the "Count Up" printf values into the "old_name" variable of the rename function. Same thing with the "Count Down" printf value for "new_name".

Code:

#include <stdio.h>
#define PREFIX "_MG_"
#define EXT ".JPG"

int main()

{

	int start_suffix = 7398, end_suffix = 8199, suffix = 9010;

	while (start_suffix <= end_suffix ) {

	// Count Up
	printf("%s%04d%s",PREFIX, start_suffix, EXT);
	start_suffix++;

	// Count Down
	printf("%s%04d%s\n",PREFIX, suffix, EXT);
	suffix--;

	rename("old_name", "new_name");
	}
	return 0;
}

The print output is exactly what I want for the renaming of the files. Now if I just could get those values into the rename function I think my program will be OK. Thanks.

You can use sprintf to write to a string, just like you use printf to print to the screen. You just have to have a way of making sure the string written to is always big enough to hold the result.

Thanks King Mir ....... I am looking at sprintf in my book and that looks like the solution. It's late now and I will try it tomorrow and post back with the results. Thanks

This is a bit of code I use to name an unknown amount of output files:

filename[] is a char array, with the first 5 letters being "Quest". Then the appropriate
filenumber (an unsigned long int), is appended to that name to make:

Quest1
Quest2
...
Quest770

That's as high as I have used it, to date - no problems.

Code:

 //close this file, open a new file
                        fclose(out);
                        ++filenum;
                        ultoa(filenum, afilenum, 10);
                        strcat(filename, afilenum);

                        if((out == fopen(filename, "wt")) == NULL) {
                          printf("\nUnable to open file: %s ", filename);
                          printf("\n Program Terminated - Press Enter When Ready");
                          gar = getchar();
                        }
                        filename[5] = '\0';

Still having problems. I get this compiling error:

14: error: incompatible types in assignment
18: error: incompatible types in assignment

And I still can't figure out the correct syntax for passing variables into the rename function.

Code:

#include <stdio.h>
#define PREFIX "_MG_"
#define EXT ".JPG"

int main()

{
	int start_suffix = 7398, end_suffix = 8199, suffix = 9010;
	char old_name[15], new_name[15];

	while (start_suffix <= end_suffix ) {

	// Old file name - Count up
	old_name = sprintf("%s%04d%s",PREFIX, start_suffix, EXT);
	start_suffix++;

	// New file name - Count down
	new_name = sprintf("%s%04d%s\n",PREFIX, suffix, EXT);
	suffix--;

	rename("old_name", "new_name");
	}
	return 0;
}

Adak ..... I don't see the rename function in your code. Is there another C function that renames files? Perhaps ultoa or strcat?

So you can never assign anything ever to an array name. You should look up sprintf again, and notice where the answer is (hint: not the return value).

Ok .......Thanks for all the replies. I decide to code it in PHP and run it from the terminal and it works as I wanted it to.





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Len