PHP Data type Conversion _php Tutorial

PHP does not need (or does not support) explicit type definitions in variable definitions; The variable type is determined by the context in which the variable is used. In other words, if you assign a string value to a variable var， varis a string. If you assign an integer value to the var, then it becomes an integer.

An example of automatic type conversion for PHP is the plus sign "+". If any one operand is a floating-point number, all operands are treated as floating-point numbers, and the result is a floating-point number. Otherwise the operand is interpreted as an integer, and the result is an integer. Note that this does not change the type of the operands themselves; it only changes how the operands are evaluated and the type of the expression itself.

Type casting

The allowable casts are:

• (int), (integer)-Convert to Integer (integer)
• (bool), (Boolean)-Converts to Boolean (Boolean)
• (float), (double), (real)-Convert to floating-point (float)
• (string)-Convert to string (string)
• (binary)-converted to binary string ( string) (PHP 6)
• (array)-converts to arrays (array)
• (object)-Convert to object (objects)
• (unset)-Convert to NULL (PHP 5)

The (binary) conversion will precede the result with the prefix ' B ', PHP 5.2.1 new.

Note that spaces and tabs are allowed inside the parentheses

Converts string literals and variables to binary strings (string):

 
  < span="">= (binary  < span="">    < span="">    )< span="">  = B "binary string"< span="">?>

If you want to change the type of a variable, see Settype ();

Settype - Set the type of the variable

BOOL Settype( mixed $var , string $type )

Set the type of the variable var to type.

The possible values for type are:

• "Boolean" (or "bool", starting from PHP 4.2.0)
• "Integer" (or "int", starting from PHP 4.2.0)
• "Float" (only available after PHP 4.2.0, for "double" used in older versions is now disabled)
• "String"
• "Array"
• "Object"
• "Null" (from PHP 4.2.0)

Returns TRUEon success, or FALSEon failure.

Intval (), Floatval (), Strval (), these three functions can also be converted

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