Thread: Compare files

Hello everyone, this is my first post.

I need help on my assignment, hope someone can guide me.
In short, I need to using C, compare two (text )files and see whether the contents are the same or not.
The percentage of similarity are finally print on screen.

For example:
================================================== ====
1. enter source file
2. enter the file you want to compare against

Result:
The % match is: 50%
================================================== ====

I'am not asking anyone to do for me, but just some guide on how to approach.
Thank in advance!

If you ever get bored you can make it more like diff you could look at theire source and have a little fun

Thank for the above post.

I try the code without any result:

if( fgetc( file1 ) == fgetc( file2 ) )
match++;
else
mismatch++;

==========================
FILE *pFile1;
FILE *pFile2;
int i=0;
int i2=0;

pFile1= fopen("source.txt", "r");
pFile2= fopen("Reference.txt", "r");

if( fgetc( pFile1) == fgetc( pFile2) )
i++;
else
i2++;
=============================

I noticed the method compare character by character, which might not be a good way.
I think it's better to compare sentence(s).

My code:

char name[100] ;
int size;

while(!feof(pFile1))
{

fscanf(pFile1,"%s",name);
size = strlen(name) + 1;

s[i] = (char *)malloc(size*sizeof(char));
strcpy(s[i], name);
i++;
}

Thank for the above post.

I try the code without any result:

if( fgetc( file1 ) == fgetc( file2 ) )
match++;
else
mismatch++;

==========================
FILE *pFile1;
FILE *pFile2;
int i=0;
int i2=0;

pFile1= fopen("source.txt", "r");
pFile2= fopen("Reference.txt", "r");

if( fgetc( pFile1) == fgetc( pFile2) )
i++;
else
i2++;
=============================

I noticed the method compare character by character, which might not be a good way.
I think it's better to compare sentence(s).

I have did some, copy the entire content but only limit to 100 words.
Can someone suggest a better ideas?

My code:
char *s[100];
char name[100] ;
int size;

while(!feof(pFile1))
{

fscanf(pFile1,"%s",name);
size = strlen(name) + 1;

s[i] = (char *)malloc(size*sizeof(char));
strcpy(s[i], name);
i++;
}

Originally Posted by linuxdude

If you ever get bored you can make it more like diff you could look at theire source and have a little fun

I agree. Look into how diff is done. Also look into longest matching substrings and sequence alignment. Or you could take a list of all the words and see how many match, irrespective of their context.

You can define the comparison anyway you want but if you were to compare character by character then adding a single character causes the 2 files to be considered entirely different, even though they are almost entirely the same.

It all depends on what the contents of the text files are that you want to compare.

Thank for the above replies, i'm very busy so never check the forum this few days.

You might be right, i am wrong in the coding. (i'm very new to C programming. )

By the way, where is Dave's code, and i can't find the code for diff, i check the link but no code is given.

Hi, this is my program, have to hand in this assignment tomorrow.
Please help me by taking a look.

Give some advice on mistake or improvement.

Done in MS VS 6.0
To test this program, you need a few small text files in the same directory as the project. (txt files only)

fflush(stdin);
this is bad see faq. Do you mean fflush(stdout)? It is not good to call main recursivly use a while loop instead. What I can do is hit a key that isn't a choice over and over and crash you computer Don't use feof for a control loop. See faq. I guess you could turn it in like that if your teacher isn't that smart

Thank for yor response!
Anyone, anymore?

By the way, my teacher very strict, he like to check every single line of code, and compare your work with other students espeically.