File comparison in c++

[mickey22]

Hi all,

I have to perform binary comparison of the generated files each time I build my program.

For example in my first build I generate a header file and data file and store them in reference directory. Next time when I build the program again I will be generating the same files and I have to compare the ones in my reference directory if they are same. I have seen different utility programs that performs file comparison on the command line. But I have to include this comparison in my program and generate a file if there are any differences in the files.

Could anyone please help me with this?

P.S: I am working on Visual 2005 and it is console application.

Thanks.

[Savage]

Hi all,

I have to perform binary comparison of the generated files each time I build my program.

For example in my first build I generate a header file and data file and store them in reference directory. Next time when I build the program again I will be generating the same files and I have to compare the ones in my reference directory if they are same. I have seen different utility programs that performs file comparison on the command line. But I have to include this comparison in my program and generate a file if there are any differences in the files.

Could anyone please help me with this?

P.S: I am working on Visual 2005 and it is console application.

Thanks.

And how is ur programm building files?

Is it line by line or char by char?

Savage

[mickey22]

My program generates for example the header file through a system commandand it is like text file with characters and numbers.On the other hand a data file is created containing ASCII characters.Each time I build my program I run these system commands and new version of files are created.
I guess answer to your question, my program is building line by line.
I did not exactly understand the question.

Please let me know if you need more information.

Thanks.

[Savage]

My program generates for example the header file through a system commandand it is like text file with characters and numbers.On the other hand a data file is created containing ASCII characters.Each time I build my program I run these system commands and new version of files are created.
I guess answer to your question, my program is building line by line.
I did not exactly understand the question.

Please let me know if you need more information.

Thanks.

Ok so it's line by line which means that u can create a simple while loop which will loop until eof is reached and files are not updated.In loop body u must test those lines for equlaity and if new line is different from line in file replace it in ur file.

Savage

[AdrianH]

Hi all,

I have to perform binary comparison of the generated files each time I build my program.

For example in my first build I generate a header file and data file and store them in reference directory. Next time when I build the program again I will be generating the same files and I have to compare the ones in my reference directory if they are same. I have seen different utility programs that performs file comparison on the command line. But I have to include this comparison in my program and generate a file if there are any differences in the files.

Could anyone please help me with this?

P.S: I am working on Visual 2005 and it is console application.

Thanks.

Why do you have to do a binary comparison exactly? What do you hope to achieve?

I'm asking this because doing a binary comparison may not be the best most efficient way of doing what you are attempting to do. It might be, but I am just giving you some other option.


Adrian

[mickey22]

I have to do this for debugging purposes.In case if there are any differeneces between the files when comparison is done, it means that code has been updated somewhere.

I am stiull not clear how to start this.Could you please explain me more clear how to get started.Just have to make it simple comparison.

Please let me know if any questions.

Thanks.

[Savage]

I have to do this for debugging purposes.In case if there are any differeneces between the files when comparison is done, it means that code has been updated somewhere.

I am stiull not clear how to start this.Could you please explain me more clear how to get started.Just have to make it simple comparison.

Please let me know if any questions.

Thanks.

What exactly confuse u?Do u know to use functions for data reading?

Savage

[mickey22]

Just wanted to make clear what u said is if it is large data file with ASCII char's I need to parse through each value in the file and check for equality?

I also need some help with the functions.Could you please tell me what kind of functions I can use?

Thanks

[Savage]

Just wanted to make clear what u said is if it is large data file with ASCII char's I need to parse through each value in the file and check for equality?

I also need some help with the functions.Could you please tell me what kind of functions I can use?

Thanks

That's the best way to be sure that files (don't)match.

Use fgets to read in a single line,compare that line with line that u are just about to output in same file using strcmp,if there is any differance output the new line,otherway read in another line and reapet same process until EOF.

Savage

[AdrianH]

I have to do this for debugging purposes.In case if there are any differeneces between the files when comparison is done, it means that code has been updated somewhere.

I am stiull not clear how to start this.Could you please explain me more clear how to get started.Just have to make it simple comparison.

Please let me know if any questions.

Thanks.

But why reinvent the wheel? There are a bunch of utilities that do binary comparisons. Windoze uses FC, Unicies use diff.

Further, you could put a static char array at the beginning of each source and assign it to "Compiled: " __DATE__ __TIME__. It would make the object binary slightly bigger, but not only would you be able to compare the files faster (it should appear near the beginning of the object file if you make it appear at the beginning of the source file, allowing you to bail sooner when you find it), it would also tell you when it was modified.

An even faster method under Windozs is to use the archive file bit. Set all the files as archived by clearing the archive bit (use attrib /S -A * from the correct directory) and do a recompile. Any files that are modified will have their archive bits reset. (use attrib /S to find these or make your own utility).

More generically under Unix (or using Cygwin or MinGW under Windoze), create a new file (use touch to create it) and then do a recompile. From there you would do a time stamp comparison between the file you created using touch and the files in the compile directory (use test to do this comparison). All modified ones would have a date stamp that is newer than the file you created (unless your system clock is going backwards ;) :D)

These last two methods are much faster than comparing the files against each other because you are only checking the file attributes, not the entire file. You also don't have to make a copy of the original directory (unless you want to do that for backing up).

What OS, compiler and IDE are you using?


Adrian

[mickey22]

I am using Windows OS, INTEL C++ compiler, Visual c++ 2005