Fundamentals of the C Programming Language

7/30/2019 Fundamentals of the C Programming Language

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Fundamentals of the CProgramming Language


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Objectives

C Program development environment

Elements of the C language

Program comments

Preprocessor directives Functions

Executable Statements

General form of a C program

Common Programming Errors: logic/design error,syntax error, run-time error


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The system software necessary to develop Capplication program are bundled into an integrateddevelopment environment (IDE)

A typical IDE contains text editor, C compiler,

preprocessor, libraries, other tools The C programming environment has 2

components: Language features to carry out basic operations (e.g.:

store data in variables, compare 2 data values, perform

arithmetic operation, etc.) Libraries routines to carry out operations not part of the

language (Standard libraries e.g.: #include & programmer-defined libraries)

C Program Development

Environment


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IDE Microsoft Visual C++


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1. Prepare program (and data files) Use a text editor to type your source program statements.

Assign a name to your source program file (.C) and savethe file into disk storage.

(optional) Use the text editor to create a data files. Assignnames to the data files (.txt or .dat) and save the files

2. Compile Perform by a compiler.

C compiler has 2 separate programs: the preprocessor

and the translator. Preprocessor reads the source code and prepares the

code for the translator.

Translator translates the code into machine language.


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3. Link (Build)

As we will see later, a C program is made up of

many functions.

The linker assembles all the functions into final

executable program (creates exe file).

4. Execute

If successful, it is ready for execution and get theoutput otherwise debug the program


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Output:

A Simple C Program Example


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Elements of the C language/* Example Case: Apples

Author: Mdm Badariah Solemon

*/

#include

int main()

{

int Qty;

double Cost=0.0, Total=0.0;

printf ("Enter quantity of apples purchased (in Kg):");

scanf("%d", &Qty);

printf ("Enter the cost per Kg of apples (in RM per Kg):");

scanf("%lf",&Cost);

Total = Cost * Qty;

printf("\nTotal cost of apples = %.2f\n",Total);

return 0;

}

preprocessor

directive

variable

comment

specialsymbol

reservedword

punctuation

standard header file

statement


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Program Comments

Statement in a program intended fordocumentation and clarification purposes

Have no effect on program execution.

Comments are inserted into the code using/*and */ to surround comment or// to begincomment lines./* This is a comment */

// This is known as comment line

/* The comments can span into morethan one lines */


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Preprocessor directives

The C program line that begins with # provides an

instruction to the C preprocessor

It is executed before the actual compilation is done.

Two most common directives : #include

#define

In our example (#include) identifies the

header file for standard input and output needed by

the printf().


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Functions

Every C program has a functionmain

The functionmain usually calls input/outputfunctions printf(),scanf(), etc.

These input/output functions are discussed inChapter 4. The word main is a C reservedword. We must

not use it for declaring any other variable orconstant.

4 common ways ofmain declaration:int main(void)

{

return 0;

}

void main(void)

{

}

main(void)

{

}

main( )

{

}


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The curly braces { } identify a segment / bodyof a program

The start and end of a function

The start and end of the selection or repetitionblock.

Since the opening brace { indicates the startof a segment with the closing brace indicating

the end of a segment, there must be just asmany opening braces as closing braces }(this is a common mistake of beginners)


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Statements

A specification of an action to be taken by thecomputer as the program executes.

Each statement in C needs to be terminated withsemicolon (;)

Example:

#include

void main(void)

{

printf(I love programming\n);printf(You will love it too once );

printf(you know the trick\n);

}


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Statement has two parts :

Declaration

The part of the program that tells the compiler the

names of memory cells in a program

Executable statements

Program lines (excluding comments) that areconverted to machine language instructions andexecuted by the computer.

A list of statements may be enclosed in braces {} (known as compound statement)

int age, total=0.0;


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preprocessor directives

main function heading

{

declarations

executable statements

}

#include

void main(void)

{

// statement(s);

}


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C statements can extend over more than one

line. Example:

printf (\n Your coins are worth %d dollarsand %d cents.\n, dollar, change);

You can write more than one statement on a

line (but not recommended). Example:

printf(Enter your name:); scanf(%,&Name);


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Common Programming Errors

Debugging - Process removing errors from

a program

Three (3) kinds of errors :

1. Syntax Error

a violation of the C grammar rules, detected during

program translation (compilation).

statement cannot be translated and program cannotbe executed


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2. Run-time errors

An attempt to perform an invalid operation, detected

during program execution.

Occurs when the program directs the computer toperform an illegal operation, such as dividing a

number by zero.

The computer will stop executing the program, and

displays a diagnostic message indicates the line

where the error was detected **

** depends on IDE Ms Visual Studio: warning


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3. Logic Error/Design Error

An error caused by following an incorrect algorithm

Very difficult to detect - it does not cause run-time

error and does not display message errors. The only sign of logic error incorrect program output

Can be detected by testing the program thoroughly,

comparing its output to calculated results

To prevent carefully desk checking the algorithmand written program before you actually type it


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Summary

You learned about: C Program development environment

Elements of the C language

Program comments Preprocessor directives

Functions

Executable Statements


Common Programming Errors: syntax error, run-time error,

logic/design error.

Fundamentals of the C Programming Language

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