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MASTERING C WITH MC KENZIE

Lesson One

A Simple C Program - Hello World

You Will Learn About :

• The Structure of a C program
• The Main function
• Using the Newline character

A C program is made up of one or more of functions. A function is a group of related statements. One function must be named main( )

There are rules for all spoken languages. C a computer language also has rules which the programmer must observe.

Here are some to commit to memory.

1. C is case sensitive. Use lowercase or common letters for all functions.
2. Every C program must have a function called main( )
3. All functions must begin with an opening brace { and end with a closing brace }
4. All statements end with a semi-colon

/* Program 1A - Hello Program */ main() {    printf("Hello, world");    }

Instructions :

• Compile source code and correct syntax errors
• Save the program as prog1.C
• Run the program.

Detailed Explanation :

1. main( ) and printf( ) are written in lower case characters.
2. Comments must be preceded by /* and ended with */ Do not separated the asterisk from the slashes with a space . This    /    *     will not work
3. Comments may be written above, below or even within the body of the function called main( ).
4. The printf( ) function is used to display a message on screen. Double quotes are needed around the message to be displayed.

C does not care how the program is written as long as all of the syntax rules are followed. The next program, Program 1B , looks bad to the reader but not to the C compiler

Clear Code

The compiler is the program which converts the code you write ( source code ) into object or machine code which the computer "understands". We need to present our code in a readable format for the benefit of other programmers and ourselves but the computer does not care.

/* Program 1B - Fun Program */ main(){printf("this is fun");}

The sequence `\n' is C notation for "newline character", which, when printed, skips the terminal to the beginning of the next line. Notice that `\n' represents only a single character.

/* Program 1A - Hello Program */ main() {    printf("I am glad \n to be learning C programming");    }

The \n newline character forces the words "to be learning C programming" to begin on a new line.