Everyone will come into contact with operators when learning programming languages. This article mainly shares with you a collection of PHP operators, hoping to help everyone.
1. Operator precedence
Increment/Decrease> ! > Arithmetic operators> Size comparison> (Not)Equality comparison> Reference>
Bit operator (^ ) > bit operator (|) > logical AND > logical OR > ternary > assignment > and > Use
2. Comparison operators
2.1, the difference between == and ===
==: Comparison value
===: Comparison value and comparison type
2.2. Judgment of equality (seven cases of FALSE)
0, 0.0, ' ', '0', false, array(), null
2.3. Increasing and decrementing does not affect the Boolean value
2.4. Decreasing the NULL value has no effect, but increasing the NULL value is 1
3. Logical operators
3.1. Short-circuit effect
$a = true || $b == 3 ;//$b is not executed
$b = false && $a == 1;//$a is not executed
3.2, || and && have different priorities from or and and
&& > || > and > or
$a = false || true; //true
$b = false or true; // false
4. Example
0 || $b = 3 > 0) * { * $a++; * $b++; * echo $a. "\n"; * echo $b. "\n"; * } */ $a = 0; $b = 0; if ($a = 3 > 0 || $b = 3 > 0) { /** * > 的优先级大于 || 大于 = * 因此可以认为是 * $a = ((3 > 0) || $b = 3 > 0) * => $a = (true || $b = 3 > 0) * 由于逻辑或短路作用,b 不再执行 * 因此:$a = true, b = 0 * 由于布尔值递增和递减都不影响还是true,而打印echo时,true底层转为1 * 因此最终echo a 和 b,都是1 */ $a++; $b++; echo $a. "\n"; echo $b. "\n"; }
Detailed explanation of php operators and expression usage examples
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