Thread: Tell me about C/C++

http://www.cprogramming.com/

int main()
{
int a, b;
int result;

a = 5;
b = 4;
a = a + 1;
result = a - b;

cout <<result<<endl;
}

It might look really confusing at first, but when you actually sit down and read it slowly, it's pretty easy to understand.

In the code I provided, I'm saying that a = 5 and b = 2, then I'm taking a and adding 1 to it, then taking the new answer of a and subtracting it from b which would give me 2.

I just started learning yesterday :3

I'm using code::blocks for my C++ writing along with the www.cplusplus.com website.

Should I learn C or C++ first?

I'm learning C++ to learn how to make my own game engine. I don't really know anything about C.

either, really
they're 80% the same
(C++ started out as an extension to C)

depends if you prefer procedural or object orientated programming

Well, it depends on what you want to do with it. C++ is better for large projects, while C is best if you're writing time-critical applications. C would also be the logical choice if you want to make other things than computer programs, like if you want to program other integrated chips.
Many hold that you should always learn C first and then move on to C++, as C++ almost is a superset of C, but either way knowing one will help you with the other.

Originally Posted by khh

Many hold that you should always learn C first and then move on to C++

I disagree with that

There's certain things that are the "right way" in C, but the "wrong way" in C++ (and vice versa)
Arrays being the biggy

You may fall into the trap of using wrong methodologies in either language

Originally Posted by Ynot

There's certain things that are the "right way" in C, but the "wrong way" in C++ (and vice versa)
Arrays being the biggy

Arrays are exactly the same in C and C++.

He's right about the right and wrong ways being different in C and C++

Critical section in C

Code:

void CriticalMethod(void){
   pthread_mutex_lock(somelock);
   //some critical stuff
   if (boolean){
      pthread_mutex_unlock(somelock);  //have to unlock in every exit path
      return;
   }
   //more critical stuff
   pthread_mutex_unlock(somelock);
}

Critical section in C++

Code:

//Autolock.h
struct AutoLock{
   public:
      AutoLock(pthread_mutex_t * lock){
         pthread_mutex_lock(lock);
         mylock = lock;
      }
      ~AutoLock(void){
         pthread_mutex_unlock(mylock);
      }
   private:
      pthread_mutex_t mylock;
}

Code:

void CriticalMethod(void){
   AutoLock lock(somelock);  //will automatically unlock when it returns
   //some critical stuff
   if (boolean){
      return;
   }
   //More critical stuff
}

***********************


What exactly would you like to know guitarboy, honoured you came to me

I learned C first, then taught myself C++. I would recommend just learning C++, most programming is done in C++, and it's a lot easier. It's also a good thing to understand object oriented programming.

Here's some things to understand, in order
Primitive types: int, long, float, char
Scope
methods and functions
pass-by-reference vs pass-by-value
const
Pointers
Objects (classes and structs)
Constructors and destructors

Feel free to IM me about anything

Originally Posted by ninja9578

Arrays are exactly the same in C and C++.

I know they are the same
but they're hailed in C, and frowned upon in C++

From the man himself
http://www2.research.att.com/~bs/bs_faq2.html#arrays

Oh, okay, you meant that in C++ you're supposed to use STL containers We still use arrays for various things though.

Actually I have a question...

I'm learning C++ and right now I'm reading about ++ and --

The example it gives me is this...

Example 1:

Code:

B=3;
A=++B;
// A contains 4, B contains 4

Example 2:

Code:

B=3;
A=B++;
// A contains 3, B contains 4

I don't really understand the whole ++ and -- and how it affects the A and B variables. Can someone explain how it adds up?

Edit: Also, how does all this make up a video game engine?

increment and decrement
(Ie. add one, or subtract one)
used all the time when looping and keeping count of things

a++ means "return the value of a, and then increment it"
++a means "increment a, then return the value"

subtle (but important) differences, however the differences between the pre & post incrementation are only important if you care about the value of a variable mid-operation

Code:

for (i = 0; i < max; i++)
{

}

and

Code:

for (i = 0; i < max; ++i)
{

}

are identical in operation
(because we do not care about the value of 'i' mid-operation

however,
say we are keeping a count of something that we later need to step back through in reverse

Code:

void increment_something(int var)
{
    old_var = var++;
}

here, we do care about the value of var mid-operation, therefore we store the "old value" of var and increment var

You can of course do this

Code:

void increment_something(int var)
{
    old_var = var;
    var++;
}

then we've split the operation into two
and now we no longer care about the return value of the increment

Originally Posted by Ynot

Code:

for (i = 0; i < max; i++)
{

}

and

Code:

for (i = 0; i < max; ++i)
{

}

are identical in operation
(because we do not care about the value of 'i' mid-operation

Almost correct. In for loops you want to do the latter because in order to return, then increment, it has to keep a copy of it. Not a problem with ints, but with objects it can.

++ and -- are weird to learn.

b = ++a; is like this:
a = a + 1;
b = a;

b = a++; is like this:
b = a;
a = a + 1;

Err...you're using some things in there I haven't learned yet. So I think you just made it more confusing for me...

Edit: Ok that makes it a little easier to understand...

So would it be something like this for the 2nd part?

b = 1;
b = a++;

Would the result be: b = 1, a = 2? Because I already defined b to equal 1 and then a equals b which is 1, then I add a to a to get 2, right?

follow a tutorial on C++
I've always liked this one
http://www.cprogramming.com/tutorial/lesson1.html

It'll take you through the basics, and slowly build up to more complex things

*edit*
Just realised you're not the OP.....

Lol no I'm not

But I'll make good use of this thread...

Also, I'm following this tutorial so far: http://cplusplus.com/doc/tutorial/operators/

edit: but again, how does all this make up a video game engine? Or any program?

Well, we break it up. We break down the seemingly huge task of a full program and break it down into pieces which are more manageable. We then code each part, sometimes sticking the together in one executable, but more commonly, we create a complex set of dynamic libraries.

A video game engine would probably be about a quarter of a million lines of C++ code, broken up into maybe 1000 different files.

Wow...quarter of a million...

Well I guess that adds up fast seeing how small lines of code are.

A Roxxor wants me to make a simple text based game. I'm not sure how I'm going to do this...

Well, Most of use consider lines of code as actually newline characters, including white space and comments.

What kind of game?

hangman is always a good first game

pick a random word from file of possible words
let the user guess letters
print letters found, and underscores for not found
keep a count of num guesses

Originally Posted by ninja9578

What kind of game?

Just a simple text based game. Maybe something like, "You grab a gun. What do you do next? Respond: Shoot the enemy. The enemy dies."

I'm not really sure if that's how it's going to be though...

I'm wanting to make my own game engine and A Roxxor said he would help me out. We're going to be working on a 2D side scrolling platformer. I have all the ideas in my head and some of it's written down.

I think he said he's going to be working on the level editor and I'll be learning C++ and helping Drawsher with working on the sprites for the characters.

Oh oh oh, I'm doing that too. I'm calling my game Mavio. I've got the shell of it all done, I just need to fill in my code out with the functionality

the way to plan out a programming project is to start with a large idea and break it down into lots of smaller segments
then break those segments down further, and so on

You should end up with tons of really simple operations that are a doddle to code

Code:

void player::take_damage(int damage)
{
    player.health -= damage;

    if (player.health < 0)
    {
        died();
    }
}

So far all I've learned how to do is this:
http://img503.imageshack.us/img503/2765/67539020.jpg
Which comes out to be this:
http://img99.imageshack.us/img99/6329/69704121.jpg