cutting down on code lines

Is there a way I can use multiple files for one program? Like write one lvlone.cpp for my first level functions then a new lvltwo.cpp for my second level and so on. Then when I write the playgame function just have a playlvlone(); function. I am trying to cut down on the lines of code I have to navigate through. I know there has to be a way to do it. No way modern games are made wading through a million lines of code in one file.

Sure, you can split your declarations/function prototypes into separate header files and then include them in your main program.
Here is a short example

Code:

//Level1.h
void LoadLevel1();

Code:

//Level1.cpp
#include "Level1.h"
#include <iostream>

using std::cout;
using std::endl;

void LoadLevel1()
{
	cout << "Level 1 Loaded" << endl;
}

Code:

//main.cpp
#include "Level1.h";

int main()
{
	LoadLevel1();
}

This way, you can split your code into several source files and have the main.cpp file nice and short.

Be sure to use header guards when writing headers, Spidey.

Cprogramming.com FAQ > Multiple source files for one program (C++ example)

If you've got one file per level, you're doing something wrong.

Your typical game is a few MB of program code (probably a few hundred thousand lines of code), and the rest of the DVD is program data.

Pick any program with a level editor. You can add as many levels as you like, and customise almost ad infinitum, but the actual source code doesn't change at all.

Eg.

Code:

<game>
  <level id="1">
    <map>
    </map>
  </level>
  <level id="2">
    <map>
    </map>
  </level>
  <level id="3">
    <map>
    </map>
  </level>
</game>

Adding level 4 is simple and obvious at this point


Writing a game engine is harder than writing any single level in hard code, but once you're there, you're going to have a lot more fun adding levels quite quickly rather than cranking out a wedge of new code each time.

I understand there is a way to cut down on code using other programs, but I started programming C++ and SDL less than a week ago. These little games I am making even though they are lengthy is more for my own practice and problem solving. After I feel comfortable enough with the codes and don't having to keep looking back at the last program I made to remember what my SDL load_images() function is written like and handling events, ect. Then I will look into downloading an engine or map editor for a better game.... right now I am just trying to work on a side scroller (mario 1 remnisenct). I haven't gotten anywhere near GL or directX or any 3d components. Thank you spidey and Elisa for the answer I was looking for.