Conditional Code (Day-1) Looping & Condition

© Copyright 2017 Hidaya Institute of Science and Technology
Looping & Branching

• PHP scripts are a series of instructions in a file.
• PHP begins at the top of the file and executes each instruction, in
order, as it comes to it.
• However, some scripts need to be more complicated. You may
want your script to display one page to new customers and a
different page to existing customers.
• We need our code to be smarter, we need to start asking
questions, if the bank balance is positive calculate interest if
negative charge a penalty.
• Or you may need to display a list of phone numbers by executing
a single echo statement repeatedly, once for each phone number.
Controlling the Flow of the Script

• PHP provides two types of complex
statements that enable you to perform tasks
like this — tasks that change the order in
which statements are executed:
• Conditional statements
• Looping statements
Complex Statement

• Conditions are expressions that PHP tests or
evaluates to see whether they are true or
false.
• Conditions are used in complex statements to
determine whether or not a block of simple
statements should be executed.
• To set up conditions, you compare values.
Setting Up Conditions

• Are two values equal?
• Is one value larger or smaller than another?
• Does a string match a pattern?
Setting Up Conditions

Conditional Statement
 Conditional statements are the set of commands used to
perform different actions based on different conditions.
 In PHP we have the following conditional statements:
• If
• Else
• Else if
• Switch

If Statement
 If structure is used for conditional execution of code segment.
 If something is true, then do something.
 Syntax:
if (expr)
{
Statements
}

If Statement
 <?php
if ($c > $d)
{
echo "c is bigger than d";
}
?>
In the above example, only if the condition "$c>$d" is true,
the message "c is bigger than d" is displayed

CONDITIONAL CODE
If( ) {
}
condition
// your additional code goes here
// . . .

TERMINOLOGY
parentheses
brackets
braces
( )
{ }
[ ]

CONDITIONAL CODE
If( ) {
}
condition
echo “it’s true!”;
// . . .
$a < 50
$b > 20
true or false?
$c == 99
$c === 99
$d != 100 Code block

EQUALITY
If( $a == $b ){
// execute this code
}

ASSIGNMENT INSTEAD OF EQUALITY
$a = 5;
$b = 10;
If( $a = $b ){
// always true!
}

OPERATOR WITH =
= assignment
== equality
===strict equality

COMPARISON
If( $a == $b ){ …
If( $a != $b ){ …
If( $a === $b ){ …
If( $a !== $b ){ …
If( $a > $b ){ …
If( $a < $b ){ …
If( $a >= $b ){ …
If( $a <= $b ){ …

Using comparison operators

&&
LOGICAL AND / OR
If( $a === $b $c === $d){…
If( $a === $b $c === $d){…
If( ($a > $b) && ($c > $d) ){…
and
or
||

Else Statement
 If you want to execute some code if a condition is true and
another code if a condition is false, use the if....else
statement.
 Syntax
•if (condition)
code to be executed if condition is true;
•else
code to be executed if condition is false;

Else Statement
 <?php
$c = 10;
$d = 20;
if ($c > $d) {
echo "C is bigger than d";
}
else {
echo "D is bigger than c";
}
?>
Result: D is bigger than C
In the above example in the if the condition "$c>$d" is true then the
message "C is bigger than D" is displayed, else the message "D is bigger than
C" is displayed.

Conditional Code (Day-1) Looping & Condition

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Conditional Code (Day-1) Looping & Condition