This document discusses various control structures in programming languages including sequence, selection, and repetition structures. It provides examples of each structure in C language. Sequence structures execute statements in order. Selection structures like if-else and switch direct program flow based on conditions. Repetition structures like for, while, and do-while loops repeatedly execute statements as long as a condition is true. Unconditional branching uses goto to transfer control to another part of the program.

1. Control Structures
Lesson 9
MANOLO L. GIRON
RMTU
Structure of Programming Language

2. Control Structures
• is a control statement and the collection of statements whose execution it controls.
• also known as a construct, depicts the logical order of program instructions.
• Three basic control structures are;
1. Sequence or Assignment
2. Selection
3. Repetition
4. Unconditional Branching
Structure of Programming Language

3. SEQUENCE OR ASSIGNMENT
CONTROL STRUCTURE
• A sequence control structure shows one or more actions
following each other in order.
• Actions include inputs, processes, and outputs.
• All actions must be executed; that is, none can be skipped.
Structure of Programming Language

4. • Examples of actions are reading a record, calculating averages or
totals, and printing totals.
Example using C language
average = (2+3+4)/3;
Structure of Programming Language

5. SELECTION CONTROL STRUCTURE
• A selection control structure tells the program which action to
take, based on a certain condition.
• Selection statements fall into two general categories:
1. two-way
2. n-way, or multiple selection.
Structure of Programming Language

6. Two-Way Selection Statements
• The general form of a two-way
selector is as follows:
if (expression)
{ Block of statements; }
else
{ Block of statements; }
Example using C language
if (cows > 10)
{ printf("loads of them!n");}
Else
{printf("Executing else part...!n");}
Structure of Programming Language

7. USING TERNARY OPERATOR
• ? : Operator
• The ? : operator is just like an if ... else statement except that because it is an operator
you can use it within expressions.
• ? : is a ternary operator in that it takes three values, this is the only ternary operator C
has.
• ? : takes the following form:
• if condition is true ? then X return value : otherwise Y value;
Structure of Programming Language

8. USING TERNARY OPERATOR
Example using C language
#include <stdio.h>
main()
{
int a , b;
a = 10;
printf( "Value of b is %dn", (a == 1) ? 20: 30 );
printf( "Value of b is %dn", (a == 10) ? 20: 30 );
}
Structure of Programming Language

9. N-WAY, OR MULTIPLE SELECTION
• The multiple-selection statement allows the selection of one of
any number of statements or statement groups. It is, therefore, a
generalization of a selector.
• In fact, two-way selectors can be built with a multiple selector
using ELSEIF.
Structure of Programming Language

10. N-WAY, OR
MULTIPLE
SELECTION
ELSEIF
Else-if statements are
based on the common
mathematics statement,
the conditional
expression.
General Form;
If (control_expression 1)
{statement 1}
else if(control_expression 2)
{statement 2}
else if(control_expression 3)
{statement 3}
else
{statement}
Structure of Programming Language

11. N-WAY, OR MULTIPLE SELECTION
• Example using C language
• if (cows == 5 )
• { printf("We have 5 cowsn"); }
• else if (cows == 6 )
• { printf("We have 6 cowsn"); }
• else if (cows == 7 )
• { printf("We have 7 cowsn"); }
Structure of Programming Language

12. N-WAY, OR MULTIPLE SELECTION
SWITCH
• This allows control to
flow through more
than one selectable
code segment on a
single execution.
General form is
switch( expression )
{
case constant-expression1: statements1;
[case constant-expression2: statements2;]
[case constant-expression3: statements3;]
[default : statements4;]
}
Structure of Programming Language

13. • char Grade = 'B';
• switch( Grade )
• {
• case 'A' : printf( "Excellentn" );
• break;
• case 'B' : printf( "Goodn" );
• break;
• case 'C' : printf( "OKn" );
• break;
• case 'D' : printf( "Mmmmm....n" );
• break;
• case 'F' : printf( "You must do better than thisn" );
• break;
• default : printf( "What is your grade anyway?n" );
}
Produce result
Good
Structure of Programming Language

14. Repetition Control Structure
• The repetition control structure enables a program to perform
one or more actions repeatedly as long as a certain condition is
met.
• Many programmers refer to this construct as a loop.
Structure of Programming Language

15. FOR Statement
• The general form of C’s for statement is
for( expression1; expression2; expression3)
{
Single statement
or
Block of statements;
}
#include <stdio.h>
main()
{
int i;
int j = 10;
for( i = 0; i <= j; i ++ )
{
printf("Hello %dn", i );
}
}Structure of Programming Language

16. WHILE Statement
• The following forms:
while ( expression )
{
Single statement
or
Block of statements;
}
Example
#include <stdio.h>
main()
{
int i = 10;
while ( i > 0 )
{
printf("Hello %dn", i );
i = i -1;
}
}
Structure of Programming Language

17. do...while loop statement
• Basic syntax of do...while loop is as follows:
• do
• {
• Single statement
• or
• Block of statements;
• }while(expression);
#include <stdio.h>
main()
{
int i = 10;
do{
printf("Hello %dn", i );
i = i -1;
}while ( i > 0 );
}Structure of Programming Language

18. Unconditional Branching
• An unconditional branch statement transfers execution control to a specified
location in the program.
• The unconditional branch, or goto, is the most powerful statement for
controlling the flow of execution of a program’s statements.
• A command that transfers control to the location that is the value of the
variable.
Structure of Programming Language

19. • SYNTAX
GoTo command
Rem Program to demonstrate the
Rem GoTo command.
Rem OUTPUT: text on the screen
Cls
Print “Hello World!”
Print “How are you?”
A GoTo L1
B Print “I’m fine.”
C L1: Print “Goodbye!”
Structure of Programming Language

20. Assignment
1. Example of code Assignments statement using C#, Python, Ruby language.
2. Example of code programs using if_then_else statement in C#, Python, Ruby
language.
3. Example of code program using ELSEIF statement in C#, Python, Ruby language.
4. Example of program using Switch statement in C#, Python, Ruby language.
5. Example of program using any loop statement in C#, Python, Ruby language.
Structure of Programming Language