Conditional statements are used to perform different actions based on different conditions.
PHP Conditional Statements
Very often when you write code, you want to perform different actions for different conditions. You can use conditional statements in your code to do this.
In PHP we have the following conditional statements:
ifstatement - executes some code if one condition is trueif...elsestatement - executes some code if a condition is true and another code if that condition is falseif...elseif...elsestatement - executes different codes for more than two conditionsswitchstatement - selects one of many blocks of code to be executed
PHP - The if Statement
The if statement executes some code if one condition is true.
Syntax
if [condition] {
code to be executed if condition is true;
}
Example
Output "Have a good day!" if the current time [HOUR] is less than 20:
Try it Yourself »
PHP - The if...else Statement
The if...else statement executes some code if a condition is true and another code if that condition is false.
Syntax
if [condition] {
code to be executed if condition is true;
} else {
code to be executed if condition is false;
}
Example
Output "Have a good day!" if the current time is less than 20, and "Have a good night!" otherwise:
Try it Yourself »
PHP - The if...elseif...else Statement
The if...elseif...else statement executes different codes for more than two conditions.
Syntax
if [condition] {
code to be executed if this condition is true;
} elseif [condition] {
code to be executed if first condition is false and this condition is true;
}
else {
code to be executed if all conditions are false;
}
Example
Output "Have a good morning!" if the current time is less than 10, and "Have a good day!" if the current time is less than 20. Otherwise it will output "Have a good night!":
Try it Yourself »
PHP - The switch Statement
The switch statement will be explained in the next chapter.
PHP Exercises
[PHP 4, PHP 5, PHP 7, PHP 8]
elseif, as its name suggests, is a combination of if and else. Like else, it extends an if statement to execute a different statement in case the original if expression evaluates to false. However, unlike else, it will execute that alternative expression only if the elseif conditional expression evaluates to true. For example,
the following code would display a is bigger than b, a equal to b or a is smaller than b:
There may be several elseifs within the same if statement. The first elseif expression [if any] that evaluates to true would be executed. In PHP, you can also write 'else if' [in two words] and the behavior would be identical to the one of 'elseif' [in a single word]. The syntactic meaning is slightly
different [if you're familiar with C, this is the same behavior] but the bottom line is that both would result in exactly the same behavior.
The elseif statement is only executed if the preceding if expression and any preceding elseif expressions evaluated to false, and the current elseif expression evaluated to true.
Note: Note that
elseifandelse ifwill only be considered exactly the same when using curly brackets as in the above example. When using a colon to define yourif/elseifconditions, you must not separateelse ifinto two words, or PHP will fail with a parse error.
Vladimir Kornea ¶
15 years ago
The parser doesn't handle mixing alternative if syntaxes as reasonably as possible.
The following is illegal [as it should be]:
This is also illegal [as it should be]:
But since the two alternative if syntaxes are not interchangeable, it's reasonable to expect that the parser wouldn't try matching else statements using one style to if statement using the alternative style. In other words, one would expect that this would work:
Instead of concluding that the else statement was intended to match the if[$b] statement [and erroring out], the parser could match the else statement to the if[$a] statement, which shares its syntax.
While it's understandable that the PHP developers don't consider this a bug, or don't consider it a bug worth their time, jsimlo was right to point out that mixing alternative if syntaxes might lead to unexpected results.
mparsa1372 at gmail dot com ¶
1 year ago
The if...elseif...else statement executes different codes for more than two conditions.
Syntax:
if [condition] {
code to be executed if this condition is true;
} elseif [condition] {
code to be executed if first condition is false and this condition is true;
} else {
code to be executed if all conditions are false;
}
Example:
Output "Have a good morning!" if the current time is less than 10, and "Have a good day!" if the current time is less than 20. Otherwise it will output "Have a good night!":
qualitycoder ¶
7 years ago
The reason 'else if' [with a space] works with traditional syntax and not colon syntax is because of a technicality.
In this instance, the 'else if' is a shorthand/inline else statement [no curly braces] with the if statement as a body. It is the same things as:
If you were to write this with colon syntax, it would be: