Replacing N'th token in a file.

kobi_hikri · #1 23-Jun-2005, 16:15

Hey.

I want to replace the N'th token found at byte number N with a new token.
I wrote the function to find the N'th character and it works just fine.
Here is my code :

CPP / C++ / C Code:

char *nth(FILE *my_file,int n)
{
	long lData_Size = sizeof(char);
	long file_size;
	char *buffer = NULL;

	//Calculate file size.
	fseek (my_file,No_Offset,SEEK_END);
	file_size = ftell (my_file);
	rewind (my_file);
	if (file_size < (long)n)
		printf("The File doen't contain %i characters.\n",n);
	else
	{
		if (fseek(my_file,n,SEEK_SET) == fseek_Failure)
			printf("fseek failed.\n");
		else
			fread (&buffer,Number_Of_Bytes,lData_Size,my_file);	
	}
	fclose(my_file);

	return(buffer);
}

I need direction with how to insert my own token into the file.
For example :
If I have the file :

my_file.txt
----------
first line
second line

and I want to use replace(my_file,5,"kobi") than the file would now be :

my_file.txt
----------
firskobi line
second line

But, If I use replace(my_file,1,"kobi") the result would be :

my_file.txt
----------
kobi line
second line

I came upon this issue while writing the assembler I told you guys about.
Any reference or idea would be most welcome.

Respect,
Kobi.

nkhambal · #2 23-Jun-2005, 20:18

Assuming the file you are trying to edit is arranged in certain structured manner when it was fist created, IMO one way to do it would be to read in the whole file into a runtime memory buffer (linked list of some sort), if the match for the token to be replaced is found, update the buffer and write the whole buffer back to the same file. Its as good as creating a new file with updated data.

This may not be the most efficient way of doing it but should get you started in the some direction.

kobi_hikri · #3 24-Jun-2005, 03:00

Quote:

Originally Posted by nkhambal

This may not be the most efficient way of doing it but should get you started in the some direction.

Thanks, but I am looking for an efficient way of doing the task. I want to update locally.

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