How to use PHP operators and detailed explanations of common problems

PHP is a commonly used server-side scripting language, and the use of operators is very important. This article will explain in detail how to use PHP operators and common problems, and provide readers with a tutorial-like usage guide.

1. Classification of operators

1. Arithmetic operators: used to implement basic arithmetic operations.
2. Assignment operator: used to assign values ​​to variables.
3. Comparison operators: used to compare the size, equality, etc. between two values.
4. Logical operators: used to implement logical operations, including AND, OR, NOT, etc.
5. Bit operators: Mainly used for processing binary data, such as bitwise AND, bitwise OR, bitwise negation, etc.
6. Operator combination: including ternary operator, range operator, etc.

2. Arithmetic operators

The arithmetic operators supported by PHP include addition, subtraction, multiplication, division and remainder. The symbols for addition, subtraction, multiplication, division and remainder are respectively " " ,"-","*","/"and"%".

The following is a sample code:

$a = 10; 
$b = 20; 
$c = $a + $b; 
echo $c; // 输出 30

In the above code, "$a $b" means adding two variables and saving the result in another variable "$c" middle. The "echo" function is used to output the value of "$c" to the screen. The output result here is "30".

3. Assignment operator

PHP supports the common assignment symbol "=", which is used to assign a variable to a certain value. In addition, there are a series of operators such as addition, subtraction, multiplication, division, modulus, etc.

The following is a sample code:

$a = 10; 
$b = $a; // $b 中的值为 10
$a += 5; // $a 中的值为 15
echo $a; // 输出 15
echo $b; // 输出 10

In the above code, the second line assigns the value of "$a" to "$b", where "$a" and "$ b" are all equal. In the third line, the addition and other assignment symbols are used to increase "$a" by 5, and then output the values ​​​​of "$a" and "$b".

4. Comparison operators

Comparison operators are mainly used to compare the size and relationship between two variables or values. Common symbols include equal to, not equal to, greater than, less than, greater than or equal to, and less than or equal to.

The following is a sample code:

$a = 10; 
$b = "10"; 
var_dump($a == $b); // 输出 bool(true)
var_dump($a === $b); // 输出 bool(false)
var_dump($a != $b); // 输出 bool(false)
var_dump($a <> $b); // 输出 bool(false)
var_dump($a !== $b); // 输出 bool(true)

In the above code, "==" indicates whether the two variables are equal, and "===" indicates that the two variables must be equal or not. To type match. Since "$b" is a string, its type does not match the type of "$a", so the result is "false".

5. Logical operators

Logical operators are mainly used to implement logical operations, including AND, OR, NOT, etc. Common logical operators include and, "&&", or, "||", not "!", etc.

The following is a sample code:

$a = true;
$b = false;
var_dump($a && $b); // 输出bool(false)
var_dump($a || $b); // 输出bool(true)
var_dump(!$a); // 输出bool(false)

In the above code, "$a" is true and "$b" is false. The results of logical AND, logical OR, and logical negation are false, true, and false respectively.

6. Bit operators

Bit operators are mainly used to process binary data, such as AND, OR, XOR, left shift, right shift, etc.

The following is a sample code:

$a = 0b101; 
$b = 0b111; 
var_dump($a & $b); // 输出 int(5)
var_dump($a | $b); // 输出 int(7)
var_dump($a ^ $b); // 输出 int(2)
var_dump(~$a); // 输出 int(-6)
var_dump($a << 2); // 输出 int(20)
var_dump($a >> 2); // 输出 int(1)

In the above code, "&" means bitwise AND, "|" means bitwise OR, "^" means bitwise XOR, "~" means bitwise inversion, "<<" means left shift, and ">>" means right shift. They all operate on binary numbers.

7. Operator combination

Operator combination includes ternary operator, range operator, etc.

1. Ternary operator

The syntax of the ternary operator is "$a ? $b : $c", which means that if "$a" is true, Then return "$b", otherwise return "$c".

Here is a sample code:

$a = 10; 
$b = 20; 
$c = ($a == $b) ? true : false; 
echo $c; // 输出 false

In the above code, "($a == $b)" is false, so "false" is returned.

2. Range operator

The syntax of the range operator is "$a..$b", which can generate an array within a continuous sequence. This syntax can only be used for arrays of integer values.

Here is a sample code:

$arr = range(1, 10);
var_dump($arr); 

In the above code, "range(1, 10)" returns an array containing numbers from 1 to 10.

8. Frequently Asked Questions

1. What is the difference between "==" and "===" in PHP?

"==" only compares "value", not type; "===" not only compares "value", but also compares type. So, if the values ​​are equal but of different types, then comparing with the "==" operator will result in true, but comparing with the "===" operator will result in false.

2. Why does continuous assignment return the value of the first variable?

This is because continuous assignment assigns values ​​from right to left, so it assigns values ​​to the rightmost variable first, and then assigns values ​​to the left in turn. Because the rightmost variable has no dependencies on other variables, its value is returned. If the rightmost variable is assigned an expression, the value of that expression is returned.

3. How to determine the maximum value among several numbers in PHP?

You can use the "max()" function.

$arr = array(1, 2, 3, 4, 5, 6);
echo max($arr); // 输出6

4. Summary

This article explains in detail the use of PHP operators and common problems, including arithmetic operators, assignment operators, comparison operators, logical operators, and bit operators , operator combinations, etc. Proficiency in these operators can speed up PHP development and improve the quality of code.

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