PHP data types, operators, and process controls

Data type Partitioning

1. Scalar type: int float string bool

2. Composite type: Array Object

3. Special type: null resource

Integer type: (int integer)

Three kinds of binary notation:

1. Decimal: 123

2. Eight binary: 0123

3.16 Binary: 0x123

Binary conversion: decimal to Binary decbin (), except 2 to write backwards

The English words in the system

Dec: Decimal

Bin: Binary

Oct: Octal

Hex: Hex

PHP conversion function: Decbin (decimal to 2 binary) (other conversions, etc.)

Note: decimal to other binary results is a string, and the other binary to decimal requires the given data to be in string form

Float type: Float document Real

String Type: String

Single quote: The contents of the output quotation marks are not escaped

Double quotation marks: outputs the contents of the quotation marks and escapes (interprets the contents of the quotation marks)

Boolean type: BOOL Boolean

Type of array: array

Definition $v1=array (1,2,3,4);

Type: Object

Resource type: Resource basically refers to a reference to external data. (data not generated by PHP code)

Null value type: null

Common functions related to data types

Var_dump (): The ability to output the full information of a variable

GetType (): Gets the type name of a variable, and the result is a string

SetType (): Sets the type of a variable setType (variable name, target type)

Isset () Determine if a variable has data

Empty () to determine if a data is null

unset (): Delete a variable

Operator:

Null decrement is invalid, increment result is 1

String merge operation: use.

Three-mesh operators:

Data 1? Data 2: Data 3

Bitwise operators: Bitwise operators are all based on the binary numeric form of integers

Bitwise AND Operation basic rules (rule table):

1 & 1 ==> 1

1 & 0 ==> 0

0 & 1 ==> 0

0 & 0 ==> 0;

3, bitwise or arithmetic basic rule

1 | 1 ==> 1;

1 | 0 ==> 1;

0 | 1 ==> 1

0 | 0 ==> 0

4, bitwise non-operation:

~ 1 ==> 0

~ 0 ==> 1

5, Bitwise XOR OR operation:

1 ^ 1 ==> 0

0 ^ 0 ==> 0

1 ^ 0 ==> 1

0 ^ 1 ==> 1

Rule: The same is 0, the difference is 1

Bitwise left-shift Operation:<<

a << n;//a is a number to be moved, the same can be a normal number, but by binary to operate, n is a specified to move

Bitwise RIGHT SHIFT operation:>>

a >> n;//a is a number to be moved, the same can be a normal number, but by binary to operate, n is a specified to move

Original code anti-code complement

Original code: is "The original binary code"

Inverse code: The inverse of a positive number is its own.

Complement: A positive complement is its own.

Array operators

Note: In PHP, the order of the elements of an array is not determined by the subscript (key name), but by the order in which they are added.

Union (+): Merges the right-hand array items behind the left array to get a new array. If there is a duplicate key, the result will be the left

Cases:

$v 1 = Array (1, 2, 3, 4);

$v 2 = array (5,6,7,8,9);

$r 1 = $v 1 + $v 2; The result can only be: Array (1,2,3,4,9)

Precedence of Operators

• Be aware that operators have priority issues
• Parentheses are the top priority, the assignment is the most backward (usually)
• First multiplication and then minus

Approximate: arithmetic operator "comparison operator" logical operator (except for "non" operation)

If statement

If Else statement:

if (conditional judgment) {

Branch 1

}

else{

Branch 2;

}

Switch statement:

Switch (a data $v1) {//To determine if this V1 variable is equal to one of the following, and if it is equal, enter the corresponding process.

Case Status value 1:

Process 1

[Break;]

Case Status Value 2:

Process 2

[Break;]

Case Status Value 3:

Process 3;

[Break;]

。。。。。。

[Default:

The default process.

]

}

Looping statements

$v 1 = 10; Initializing a loop variable

while ($v 1〉4) {//Determine the condition of the loop variable

Statement Fast

echo "ABC";

$v;

}

do{

Loop body

}while (conditional judgment);

PHP data types, operators, and process controls