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subtracts the value of the right variant from the left variant value and returns the result (PHP 5)
mixed variant_sub ( mixed left, mixed right )

Subtracts right from left using the following rules:

Table 36. Variant Subtraction Rules

Both expressions are of the string typeSubtraction
One expression is a string type and the other a characterSubtraction
One expression is numeric and the other is a stringSubtraction.
Both expressions are numericSubtraction
Either expression is NULLNULL is returned
Both expressions are emptyEmpty string is returned

See also variant_add().


As with all the variant arithmetic functions, the parameters for this function can be either a PHP native type (integer, string, floating point, boolean or NULL), or an instance of a COM, VARIANT or DOTNET class. PHP native types will be converted to variants using the same rules as found in the constructor for the VARIANT class. COM and DOTNET objects will have the value of their default property taken and used as the variant value.

The variant arithmetic functions are wrappers around the similarly named functions in the COM library; for more information on these functions, consult the MSDN library. The PHP functions are named slightly differently; for example variant_add() in PHP corresponds to VarAdd() in the MSDN documentation.