


Explain the Difference Between `==` and `===` Operators in PHP
Jul 09, 2025 am 01:03 AMIn PHP, the main difference between == and == is the strictness of type checking. The == operator performs type conversion when comparing, while === strictly checks the values ??and types without conversion. For example: "5" == 5 returns true but "5" === 5 returns false; 0 == false is true but 0 === false is false; null === 0 is always false. You should use == when the type is independent or requires flexible comparison, such as user input processing; if the type must be consistent, such as the detection function returns false, validation null or boolean flag. It is recommended to use === first to avoid logical errors caused by type conversion.
In PHP, the ==
and ===
operators are both used for comparison, but they behave differently depending on what you're comparing. The main difference lies in how strict they are about data types.

What Does ==
Do?
The ==
operator checks whether two values ??are equal after performing type juggling if necessary. This means that PHP will try to convert one or both operators to a common type before doing the comparison.
For example:

-
"5" == 5
returnstrue
because PHP converts the string"5"
into the integer5
. -
0 == false
returnstrue
becausefalse
is treated as0
in this context. -
"abc" == 0
returnstrue
because the string starts with non-numeric characters and is converted to0
.
This kind of behavior can be useful, but it can also lead to unexpected results when working with mixed types.
How Is ===
Different?
The ===
operator, also known as the identity operator , checks both value and type. It doesn't perform any type conversion — both operators must be of the same type and have the same value to return true
.

Examples:
-
"5" === 5
returnsfalse
because one is a string and the other is an integer. -
0 === false
returnsfalse
because their types different. -
null === 0
returnsfalse
, again due to different types.
Using ===
avoids ambiguity and helps prevent bugs caused by automatic type conversion.
When Should You Use Each?
Use ==
when:
- You don't care about the exact type.
- You're comparing user input (which often comes in string form) to numbers or booleans.
- You want flexibility in your comparisons.
Use ===
when:
- Type matters.
- You're checking for special values ??like
false
,null
, or-1
which might also be confused with false values. - Working with functions that can return
false
on error and also valid0
or empty values ??(likestrpos()
).
Some common cases where ===
is important:
- Checking if a function returned
false
(eg,if (strpos($str, 'a') === false)
) - Verifying if a variable is actually
null
- Ensuring that boolean flags haven't been misinterpreted from numeric or string values
Final Thoughts
Choosing between ==
and ===
depends on your use case. If you're not careful with ==
, you might run into confusing logic due to PHP's loose typing. But ===
gives you more control and prediction.
Generally speaking, using ===
is safe unless you specifically need type coercion.
The above is the detailed content of Explain the Difference Between `==` and `===` Operators in PHP. For more information, please follow other related articles on the PHP Chinese website!

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