The document provides information on various selection control structures in C programming: 1. If structure - executes statements if a condition is true. 2. If-else structure - executes one set of statements if a condition is true, and another set if false. 3. If-else if structure - checks multiple conditions in sequence. 4. Switch structure - tests a variable against multiple constant values, and executes one set of statements for true cases. 5. Goto structure - unconditionally transfers control to another part of the program.

1. UNIVERSITI TUN HUSSEIN ONN MALAYSIA
FACULTY OF MECHANICAL AND MANUFACTURING ENGINEERING
BTI 10202: COMPUTER PROGRAMMING
LAB 5 : Control Statements- Part 1 (Selection)
NAME : ____ _______________________________________ MARKS
MATRICS NO.: _______________ DATE : _____________
Objective: Introduction to various concepts of selection control structure
(Be able to choose and use the if, if..else, switch and goto selection
structures among alternatives action)
Theory:
1. if single selection structure Syntax:
If the condition is TRUE, a set of if (conditional is true)
statements are executed. {
If the condition is FALSE, the statement Statement(s);
are not executed and the program control }
goes to the next statement (after the if next statement
block) immediately.
Statement executes repeatedly as long as the value of
condition remains TRUE.
2. if double selection structure (if…else) Syntax:
If the condition is TRUE, statement A if (condition is true)
executes. When FALSE, statement {
executes. statement A;
}
else
{
statement B;
}
Next statement;
3. if multiple selection structure (if… Syntax:
else if) If (condition A)
The ‘else if’ statement is to check for a {
sequence of conditions. Statement A;
If one condition is false, it checks for the }
next condition and so on. When all the else if (condition B)
conditions are false, the ‘else’ block is {
executed. Statement B;
}
:
:
:else if (condition n)
{
Statement set-n;
}
else
{
Statement set-x;
}

2. a. Relational operators b. Equality operators
Symbol Meaning Symbol Meaning
> greater than == equal to
>= greater than or equal to != not equal to
< less than
<= less than or equal to
Note: If the selection structures have a few statements, then
c. Logical operators we need to use the curly bracket { }.
Example:
Symbol Meaning If (marks>=60)
printf(“Grade A”);
&& AND (Returns true if else if (marks<60&&marks>=30)
both conditions printf(“Grade B”);
are true) else (marks<30)
{
|| OR (Returns true if printf(“Failed”);
either of its printf(“Take a test again!”); }
conditions is
true
! NOT (Reverses the
truth/falsity of
its condition)
4. switch is useful when variable or Syntax:
condition is tested for multiple
switch (expression) {
values. It consists of a series of
case labels and an optional default case expression 1:
case. statements1;
The switch and case statements
break;
help control complex conditional
and branching operations. case expression 2:
statements 2;
break;
default:
expression n;
break;
}

3. Note: break is used to terminate loops/ exit from a switch.
Can be used within a for,while, do-while or switch
statement.
5. goto is a unconditional Syntax:
branching statement used to transfer goto name_label;
control of the program from one :
statement to another. Note: please :
ensure not to use too much goto name_label:
statements in the program because
its functionality is limited. It is only
recommended as a last resort if
structured solutions are much more
complicated.
Flowchart for selection structures Flowchart for switch control statements
(Adapted from Deitel & Deitel, C How to Program, 6th
ed., p. 111)
Example:
start:
printf(“1. Apple juicen”);
printf(“2. Mango juicen”);
printf(“Choose the fruit juice that you like?”);
scanf(“%d”,&juice);
switch(juice)
{
case 1: printf(“You like to drink apple juice”);break;
case 2: printf(“You like to drink mango juice”);break;
default: printf(“None of the fruit juice that you like!”);goto start; break;
}
Exercises:
1. What is the output for the following source code:
Output:
#include <stdio.h>
#include <conio.h>
main() {
int n = 0;
loop:

4. printf("n%d", n);
n++;
if (n<10)
{ goto loop; }
getch();
}
2. Below is a program to print RED when ‘r’or’R’ is pressed and WHITE when ‘w’ or ‘W’ is
pressed using a switch control statement. The program loops back to enter ‘r’or’R’ or ‘w’ or ‘W’
if other keys are pressed. Rewrite the coding using if-else control statements.
SWITCH program
#include<stdio.h>
#include<conio.h>
main()
{
char choice;
choose:
printf("nPlease enter 'R' for red and 'W' for whiten");
scanf("%s",&choice);
switch(choice)
{ case 'r':
case 'R':printf(" RED "); break;
case 'w':
case 'W':printf(" WHITE"); break;
IF…ELSE program
default: printf("Error!!"); goto choose; break;
}
getch();
}