The if Statement

Use the if statement to execute some code only if a specified condition is true.
Syntax
if (condition) code to be executed if condition is true;
The following example will output "Have a nice weekend!" if the current day is Friday:
< html >
< body >

< ?php
$d=date("D");
if ($d=="Fri") echo "Have a nice weekend!";
? >

< /body >
< /html >
Notice that there is no ..else.. in this syntax. You tell the browser to execute some code only if the specified condition is true.
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The if...else Statement
Use the if....else statement to execute some code if a condition is true and another code if a condition is false.
Syntax
if (condition)
code to be executed if condition is true;
else
code to be executed if condition is false;
Example
The following example will output "Have a nice weekend!" if the current day is Friday, otherwise it will output "Have a nice day!":
< html >
< body >

< ?php
$d=date("D");
if ($d=="Fri")
echo "Have a nice weekend!";
else
echo "Have a nice day!";
? >

< /body >
< /html >
If more than one line should be executed if a condition is true/false, the lines should be enclosed within curly braces:
< html >
< body >

< ?php
$d=date("D");
if ($d=="Fri")
{
echo "Hello!
";
echo "Have a nice weekend!";
echo "See you on Monday!";
}
? >

< /body >
< /html >

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The if...elseif....else Statement
Use the if....elseif...else statement to select one of several blocks of code to be executed.
Syntax
if (condition)
code to be executed if condition is true;
elseif (condition)
code to be executed if condition is true;
else
code to be executed if condition is false;
Example
The following example will output "Have a nice weekend!" if the current day is Friday, and "Have a nice Sunday!" if the current day is Sunday. Otherwise it will output "Have a nice day!":
< html >
< body >

< ?php
$d=date("D");
if ($d=="Fri")
echo "Have a nice weekend!";
elseif ($d=="Sun")
echo "Have a nice Sunday!";
else
echo "Have a nice day!";
? >

< /body >
< /html >