PHP data type conversion and type detection

This article mainly to share with you PHP data type conversion and type detection, although the basic knowledge of PHP, but very useful, I hope to help everyone.

Implicit conversions (auto-conversion)

Convert to String type

True--' 1 '

False, null, and empty string

Convert to numeric type

Start with a valid value and take it to the end of the first illegal value;

Start with a non-legal value and convert to 0

Convert to Boolean type

0, 0.0, ', ', ' 0 ', NULL, array () is false;

String, Integer, floating-point number, ' 0.0 ', ' false ', ' true '.

Show transformations

Temporary conversion

1. (variable type) $ variable name

Grammar:

Integer: (int) $ variable name

Float type: (float) $ variable name

Character type: (string) $ variable name

Boolean type: (BOOL) $ variable Name

Null: (unset) $ variable name

Number: (array) $ variable name

Object: (object) $ variable name

2. System function implementation

Intval ($ variable name) returns the value of the variable converted to an integer

Floatval ($ variable name) returns the value of a variable converted to a floating-point type

Strval ($ variable name) returns the value of the variable converted to a string type

Oolval ($ variable name) returns the value of the variable converted to a Boolean type

Permanent conversion

Settype ($ variable name, ' type ') sets the type of the variable

Detecting variable types

Integer type Is_int ()

Floating-point is_float ()

String is_string ()

Boolean type Is_bool ()

Scalar type is_scalar ()

Empty Is_null ()

Array Is_array ()

Object Is_object ()

Resource Is_resource ()

Numeric Is_numeric () in numeric or string form

Implicit conversions (auto-conversion)

Convert to String type

True--' 1 '

False, null, and empty string

Convert to numeric type

Start with a valid value and take it to the end of the first illegal value;

Start with a non-legal value and convert to 0

Convert to Boolean type

0, 0.0, ', ', ' 0 ', NULL, array () is false;

String, Integer, floating-point number, ' 0.0 ', ' false ', ' true '.

Show transformations

Temporary conversion

1. (variable type) $ variable name

Grammar:

Integer: (int) $ variable name

Float type: (float) $ variable name

Character type: (string) $ variable name

Boolean type: (BOOL) $ variable Name

Null: (unset) $ variable name

Number: (array) $ variable name

Object: (object) $ variable name

2. System function implementation

Intval ($ variable name) returns the value of the variable converted to an integer

Floatval ($ variable name) returns the value of a variable converted to a floating-point type

Strval ($ variable name) returns the value of the variable converted to a string type

Oolval ($ variable name) returns the value of the variable converted to a Boolean type

Permanent conversion

Settype ($ variable name, ' type ') sets the type of the variable

Detecting variable types

Integer type Is_int ()

Floating-point is_float ()

String is_string ()

Boolean type Is_bool ()

Scalar type is_scalar ()

Empty Is_null ()

Array Is_array ()

Object Is_object ()

Resource Is_resource ()

Numeric Is_numeric () in numeric or string form