C-programming for newbees!

By McCodEMaN

Part 4

Basics of the c-environment

All c-systems generally contains of three parts:

*The environment
*The language
*Standard directorys

C-programs passes through six phases to become executed:

*Edit
*PreProcess
*Compilate
*Link
*Load
*Execute

Edit:

In the first phase you are going to write a program by using Edit in dos or Notepad in win, the
only thing you have to remember is to write in 100% pure text.
You can not use any strange formats like: .doc .pdf .wps.........
When you have written the program you should save it on a disk in C-format, like:
CrackPatcher.c the only thing that is important is that the filename ends with a .c
It could be a good idea to use a compleate IDE = Integrated Developed Environment.
I use Borland Turbo C++ and C-builder3 Pro and i really recomend them!

PreProcessor:

When the program-code is written, it's time to compilate the textfile. The compiler translates the c-program into machine-code (objectcode).
A preprocessor program is automaticly runned in a c-system before the translation phase starts.
The c-preprocessing obey's certain commands called "Preprocessing instructions" with indicates that some kind of manipulation are to be made on the program before compilation. This manipulation can be: including of other files to the file thats being compilated or it can be changing of specialsymbols into programtext, or what ever!!

Compiler:

After PreProcessing the code is translated into machine-code.

Link:

You'll need a linker to link your code with external directorys.
A linker links the object code with the code for the missing function to produce an executable image (without missing pieces).

Loadning:

Before the program can be executed it has to be placed in memory, this is done by the
loader.
The loader takes the executable image from the disk and transform it into memory and
finally the computer executes the program under control by the CPU.

Our first C-Program

We are going to code a program that types "Learn to program with TRES2000" on
Your screen.

Here is the code:

-------------->8--------------------------->8--------------------------->8---------------------

/* C -exercise one */

                          #include <stdio.h>

                          main ()
                          {
                                printf("Learn to program with TRES2000\n");
                           }

---------------->8------------------------->8---------------------------->8---------------------

Line.1
The first line starts with: /* and end with */ this idicates that the line is a comment.
Comments are ignored by the compiler, the comment only explain the programs purpose.

Line.2
The next line is: main( )
Main is a part of all c-programs, the ( ) after main indicates that main is a program building block called function.

A c-program contains one or more functions and main has to be one.
All c-programs executes at the main function.
C-program starts to run at the first line in main and ends after the last.
Between this the program can have jumped around to a lot of places in and without
the main-function even to another main-function, which could be an other program!

Line.3
The left brace { has to start the body of all c-programs. The { in c is like
the <body> in html.

A { signals that somthing is a function and what is about to happen when it's called.

After the first { the story starts about whats happening in the function and it ends with
the right brace }

programblock which is going to be placed together in the program and are to be peformed
in the order it is, are to be within two braces so that the compiler knows that it
hangs together.

So remember: A left brace to start a function and a right brace to end the function!

Line.4

printf("Learn to program with TRES2000\n");

printf instructs the computer to perform an action, and what action is that in this case?
Yes, it instructs the computer to type: Learn to program with TRES2000 on your screen!
The line to be typed on your screen is marked by quotation marks!
The the string that will be typed on your screen is called: character string!
The entire line.4 is called: statement, the semicolon is called statement terminater and works as
a dot (.)!
So we can say to make it easy: When you terminate a line when you'r writing an essay or a mail,
you use a dot (.) but to terminate a line in C you are going to use a semicolon instead;

Note: The \n is not typed out on your screen!
           The backslash ( \ ) means escape character and idicates that printf is going to do
           something out of the ordinary.
           Backslash is used to get away from the standard sense.
           It signals that the next character that comes is a specialsign!
           The backslash combined with n makes an escape sequence that in this case (\n) means
           newline!!!

The printf-function is one of many functions in the ANSIC lib.