CHAPTER 3

OUTCOMES:
Student should be able to:
0Explain the general form 0f C
structure
0Write, Compile & Execute of C
programme
2

The general form of C
programme
3

Follow 3 steps:
0 Enter the programme
0 Compile the programme
0 Run the programme
2 terms:
0 Source code – the human readable form of the
programme. It is stored in a text file
0 Object code – the executable form of the programme
created by a compiler
4

Write the general form of C
programme
0 Entering the programme
The name of the file that holds the source code for the
programme is technically arbitrary
C programme are normally contained in files that use
the file extension (.cpp)
5

0 Compiling the programme
You can compile your .cpp file depends on your
compiler & what option you are using
e.g:
Microsoft Visual C++ Express Edition  provide 2
different ways of compiling a programme: the
command-line compiler & the Integrated Development
Environment (IDE)
6

0 Execute the debugged programme
After a C programme has been compiled, it is ready to
be run
Since the output from a C compiler is executed object
code, to run the programme, simply enter its name at
the command prompt
7

Pre-processor directives and
header files
0 Pre-processor
Is the directive to enables the programme to use certain
function contained in the external file such as <stdio.h>
0 Header file
Contain specific functions that used to accomplish the
programming task
e.g: ctype.h, math.h
8

#include
0 replaces by the whole content of specified file
0 2 ways to specify a file:
9
#include “stdio.h”
the file is looked for from the same directory in which the file
that includes the directive is
#include <stdio.h>
the file is directly looked for in the default directories where
the compiler is configured to look for standard header files

serves to generate define constants or macros
10
#define
#define variable_name value
#define pepsi 2.50
#define grapes 8.50
Example:

Create block {…} in Main
function
a function is a block of statements that is part of large
programmes
0 Function main ( )
Must have at least the function main ( )
Must have a body enclosed in braces { }
11

0 Function block { }
the function body  called block can be any size
{ - begin block
} - end block
12

Create return statement in
programmes
0 terminates the execution of a function and returns
control to the calling function
0 can also return a value to the calling function
13

Comments
0 useful for a variety of purposes
0 provide the easiest way to point out specific parts of
code
0 2 forms:
//  single line comment
/* …..*/  multi line comment
14

Single line comment
0 useful for simple ‘side’ notes that explain what certain
parts of the code do
0 places: next to variable declarations & next to pieces
of code that may need explanation
15

0 Example:
//this is first line
//this is second line
//this is third line
//this is fourth line
16

Multi line comment
0 most useful for long explanation of code
0 can be use as:
copyright/licensing notices
explain the purpose of a path of code
0 can be useful in two aspects:
make functions easier to understand
easier to spot errors in code
17

0 Example:
/*this is first line
this is second line
this is third line
this is fourth line*/
18

Create comments in programme
19
/*This is a programme that computes the sum of two integer
numbers*/
#include<stdio.h> //This is a preprocessor
main( ) //function main
{ //Begin block
int x, y, sum; //This is declaration of variable
printf(Enter first number:”); //User output
scanf(“%d”,&x); //User input
printf(Enter second number:”);
scanf(“%d”,&x);
sum= x+y; //Operation for sum of two numbers
printf(“nSum = %d”, sum); //Output
return 0; //Return statement
} //End block

CHAPTER 3

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CHAPTER 3