Advice needed for how to approach project

**The111** · 07-11-2011

I am a relatively new programmer with a decent foundation in Java (went through the entire Headfirst book last month), but I am much weaker with C/C++. I plan on going through a more comprehensive training of both at a later date, but at this moment I am committed to doing a project for school in C or C++ in a very short time frame (just over a week). I want to create a command line batch rename utility, i.e.:

command line input:
>rename *dog* *cat*

output:
dog1.jpg renamed to cat1.jpg
bigdog.zip renamed to bigcat.zip
horse.txt not renamed
etc

I knew that the first part of my program design would be searching for the replacement string in the existing filenames... but what I am just now coming to realize from scouring the web is that this functionality is not included in standard C/C++ libraries... right? It seems to require interacting with platform API's or using a 3rd party library, none of which I have experience with. At this point in time, I need to choose the right learning path to send myself down for the next few days:

1) learn the Windows API and interact with it directly from C (or C++?)
2) learn the "Microsoft Foundation Classes" (will these do what I need?)
3) learn a 3rd part library (the "Boost" filesystem library was suggested elsewhere)

If Linux is a better option I'd be receptive to that too.

Which would be the best option for me, given my experience and short timeframe? Any advice on C vs C++? I understand OO principles well from my Java experience... but I am still new to the C++ syntax so that might just be an added complication.

Thanks so much in advance for any advice!

**tabstop** · 07-11-2011

You'll want to pick an OS first. FindFirstFile/FindNextFile is a good start for windows; you'll probably want some sort of regex handler to do the name change -- I don't know of any Windows ones outside of .net, but Boost could be an option. If you're on Linux then readdir + regex.h should get you there.

**The111** · 07-11-2011

Thanks for the reply. I am pretty sure I'd like to stick with Windows.

I just found out about something called dirent.h, is that something that could help me?

**quzah** · 07-11-2011

You can always be lazy:

Code:

system( "dir whatever &> contents.txt" );
fp = fopen( "contents.txt", "r" );
if( fp )
    while( fgets( fp, buf, BUFSIZ ) )
    {
        if( strstr( buf, "dog" ) )
            dorename( buf );
    }

Quzah.

**MK27** · 07-11-2011

If the spec is a straight substitution -- arg 1 for arg 2 -- you don't need a regexp, this is a (case insensitive?) substring substitution, which in C means something that starts with strstr() or strcasestr() and continues with some splicing and possibly reallocation.

Originally Posted by The111

this functionality is not included in standard C/C++ libraries... right?

WRT to filesystem access, no. WRT internal string handling, yes.

Boost does provide a portable "filesystem" OO lib but this may be of dubious value if all you have to do is make it work on a particular platform.

Originally Posted by The111

I just found out about something called dirent.h, is that something that could help me?

Sound *nixish to me but that's me. Filesystem stuff (eg, "dir" "ls" read directory) is platform specific.

**tabstop** · 07-11-2011

dirent.h is the *nix version.

**~~CommonTater~~** · 07-11-2011

Originally Posted by The111

Thanks for the reply. I am pretty sure I'd like to stick with Windows.

I just found out about something called dirent.h, is that something that could help me?

A bit of reading ofr you ... File Management (Windows)

**The111** · 07-12-2011

Thank you so much everybody for the quick answers.

Originally Posted by tabstop

You'll want to pick an OS first. FindFirstFile/FindNextFile is a good start for windows; you'll probably want some sort of regex handler to do the name change -- I don't know of any Windows ones outside of .net, but Boost could be an option. If you're on Linux then readdir + regex.h should get you there.

Originally Posted by CommonTater

A bit of reading ofr you ... File Management (Windows)

Really stupid question incoming:

I don't really have experience using external API's. So if I am using a function called "FindFirstFile," I like to know where it is defined. So I searched the include folder of my compiler, which contains windows.h and a bunch of similar headers... I searched using wingrep for "FindFirstFile" and only got two results, winbase.h and wininet.h. Neither of these seem to actually define the function. Where is it visibly defined? I always try to understand the big picture, and it's bothering me to call a function I can't see defined. Obviously it is defined somewhere, since when I call it, it works!

Thanks!

**quzah** · 07-12-2011

Originally Posted by The111

I don't really have experience using external API's. So if I am using a function called "FindFirstFile," I like to know where it is defined. So I searched the include folder of my compiler, which contains windows.h and a bunch of similar headers... I searched using wingrep for "FindFirstFile" and only got two results, winbase.h and wininet.h. Neither of these seem to actually define the function. Where is it visibly defined? I always try to understand the big picture, and it's bothering me to call a function I can't see defined. Obviously it is defined somewhere, since when I call it, it works!

Thanks!

The MSDN was good years ago when it came on CDs with MSVC++, and I imagine it's even more complete now. But I don't know if you can actually see the source code to the function you are looking for. It will however show you the headers you need to include to use it, and typically an example of doing so.

Quzah.

**tabstop** · 07-12-2011

Originally Posted by The111

Neither of these seem to actually define the function. Where is it visibly defined? I always try to understand the big picture, and it's bothering me to call a function I can't see defined. Obviously it is defined somewhere, since when I call it, it works!

Thanks!

Are you looking for the definition or the declaration? I've never actually looked for source code for things like printf, or exp, or any of it (as interesting as it no doubt is). MSDN will have the prototype (i.e. declaration) for the function, and will also tell you what header to include.

**The111** · 07-12-2011

Originally Posted by tabstop

Are you looking for the definition or the declaration? I've never actually looked for source code for things like printf, or exp, or any of it (as interesting as it no doubt is). MSDN will have the prototype (i.e. declaration) for the function, and will also tell you what header to include.

Well, if you look at the example here:
FindFirstFile Function (Windows)

There are only 3 #include lines at the top of the program, and none of those .h files define the function "FindFirstFile" nor is it standard C. Therefore, how can I write a standard C program using a function which isn't defined in any of my included headers? That's where my confusion comes from. :-/ It works, obviously... but not sure how.

**tabstop** · 07-12-2011

Did you read the page you linked to? It's handy sometimes:

Originally Posted by MSDN

Header
WinBase.h (include Windows.h)

And there's no need for you to go grubbing through your header files: the prototype is right there at the top:

Code:

HANDLE WINAPI FindFirstFile(
  __in   LPCTSTR lpFileName,
  __out  LPWIN32_FIND_DATA lpFindFileData
);

You do have to get used to the MSDN style of documentation a bit though. (That is: __in and __out are (I believe) defined away to nothing, but they are there as a hint to you what they are for.)

**AndrewHunter** · 07-12-2011

Just look at the MSDN link quzah gave you (reproduced here for your convenience). It has the function declaration as well as explain the parameters and even provides a short example. The issue is that all these header files include other header files, which include other header files.......

The best way to navigate the windows API is by using the MSDN API library. Microsoft has a certain way of setting things up which I'm sure makes sense to somebody but isn't worth the hassle in this case. (HINT: It's all part of their plan to take over the world)

EDIT: Too slow.

**quzah** · 07-12-2011

Originally Posted by The111

"FindFirstFile" nor is it standard C. Therefore, how can I write a standard C program using a function which isn't defined in any of my included headers?

Of course it's not standard. C doesn't care anything about your file structure/system. That's why he said:

Originally Posted by tabstop

You'll want to pick an OS first.
...
I don't know of any Windows ones outside of .net, but Boost could be an option. If you're on Linux then readdir + regex.h should get you there.

You really should pay more attention.

Quzah.

**The111** · 07-12-2011

Originally Posted by AndrewHunter

The issue is that all these header files include other header files, which include other header files.......

Thank you, I guess that helps most. I did sort of find a reference to it in winbase.h that I missed before. I know I don't *need* this info to solve my problem... it's more just curiosity. Coming from tiny programming tutorials where I can *see* everything I'm #including... it's frustrating to all of a sudden have a bunch of blackbox functions thrust on me... I thought it would be neat to see where they come from, but I guess it was naive to think that source would be right out in the open.

Originally Posted by quzah

You really should pay more attention.

Classy. I guarantee there was a time you were as confused about all this as I was. I am paying attention... I am however still processing.

Furthermore, your statement "of course" is based on an incorrect assumption (for which I could tell you to pay more attention) that I was intending to declare the unknown or disagree with something currently stated; I was doing neither... it was a rhetorical question intended to explain how I got to my current state of confusion.

I do however thank you for your help... you are nearly always the first one to reply when I post here.

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