PHPのdata typeについておさらいしましょ

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Finding out the data type of a value
You can check a value's data type using one of the following PHP functions:

is_int( value )Returns true if value is an integer, false otherwise
is_float( value )Returns true if value is a float, false otherwise
is_string( value )Returns true if value is a string, false otherwise
is_unicode( value )Returns true if value is a Unicode string, false otherwise
is_binary( value )Returns true if value is a binary string, false otherwise
is_bool( value )Returns true if value is a Boolean, false otherwise
is_array( value )Returns true if value is an array, false otherwise
is_object( value )Returns true if value is an object, false otherwise
is_resource( value )Returns true if value is a resource, false otherwise
is_null( value )Returns true if value is null, false otherwise