What are the conditional assignment operators in PHP?
Introduction
Operators in PHP are signs and symbols which are used to indicate that a particular operation should be performed on an operand in an expression. Operands are the operation objects, or targets. An expression contains operands and operators arranged in a logical manner.
In PHP, there are numerous operators, which are grouped into the following categories:
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Logical operators
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String operators
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Array operators
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Arithmetic operators
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Assignment operators
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Comparison operators
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Increment/Decrement
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Conditional assignment operators
Some examples of these operators are:
+Addition-Subtraction*Multiplication/Division%Modulus><=++--and so much more.
What are conditional assignment operators?
Conditional assignment operators, as the name implies, assign values to operands based on the outcome of a certain condition. If the condition is true, the value is assigned. If the condition is false, the value is not assigned.
There are two types of conditional assignment operators: tenary operators and null coalescing operators.
1. Tenary operators ?:
Basic syntax
$y = expr1 ? expr2 : expr3;
Where expr1, expr2, and expr3 are either expressions or variables.
From the syntax, the value of ＄y will be evaluated.
This value of ＄y is evaluated to expr2 if expr1 = TRUE.
The value of $y is expr3 if expr1 = FALSE.
2. Null coalescing operators ??
The ?? operator was introduced in PHP 7 and is basically used to check for a NULL condition before assignment of values.
Basic syntax
$z = varexp1 ?? varexp2;
Where varexp1and varexp2 are either expressions or variables.
The value of ＄z is varexp1 if and only if varexp1 exists, and is not NULL.
If varexp1 does not exist or is NULL, the value of ＄z is varexp2.
Code
Let’s use some code snippets to paint a more vivid description of these operators.
<?php/*** Ternary operator ***/$expr1 = 7 > 10;$expr2 = "New y value if expr1 is true";$expr3 = "New y value if expr1 is false";//$y takes the value of $expr3 because $expr1 is false$y = $expr1 ? $expr2:$expr3;echo $y;/**** Null coalescing operator ****/echo "\n";//set varexp1 value to null$varexp1 = null;// set varexp2 value to string.$varexp2 = "new z value as varexp1 is null";$z = $varexp1 ?? $varexp2;echo $z;?>
Explanation
In the code above, the new value of ＄y and ＄z is set based on the evaluation result of expr1 and varexp1, respectively.