It refers to the data conversion value (variable) data to the target type.
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PHP There are two types of data conversion: automatic conversion, cast
Automatic conversion: system variable is the value corresponding to the type of conversion according to the type of operation required for
automatic conversion system itself things are done, the user does not need to intervene.
Cast: according to our specific needs, the value of the variable in advance converted into the desired data type
int, integer: integer, converting the data into an integer
bool, Boolean: convert the data into a Boolean value
float: converted to float -point
string: converted into character
array: into an array type of
object: Object type converted
Syntax :( data type) variable
view the data type of way
1.var_dump the type and length as well as variable data values are output
2. Type gettype function by function, access to data, returns a string
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Set the data type: settype ($ var, 'type') "========" (type) $ var
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Conversion: automatic conversion and coercion
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String transfer integer
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Automatic around: string transfer value
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rules are as follows
1. Only when the string decimal values or start the system until it is possible to convert numeric string, or else directly converted into 0
2. Read Only front continuous value, no other special characters or letters
3. a read only decimal
4. If decimal final retention, the type of data into floating-point, integer otherwise
Analyzing Data Type
PHP provides a series of functions to determine the type of data. Functions are beginning is_, followed by the data type.
If this is the type of target returns TRUE, otherwise returns FALSE
is_bool
of is_float
is_integer
is_object
is_array
is_string
is_resource
is_scalar: to determine whether the value of a variable is a scalar type
is_null
is_numeric: whether a variable is a number or a numeric string
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