variant_mul
Description
mixed variant_mul ( mixed left, mixed right )Multiplies left by right and returns the result, subject to the following rules:
表格 1. Variant Multiplication Rules
| If | Then |
|---|---|
| Both expressions are of the string, date, character, boolean type | Multiplication |
| One expression is a string type and the other a character | Multiplication |
| One expression is numeric and the other is a string | Multiplication |
| Both expressions are numeric | Multiplication |
| Either expression is NULL | NULL is returned |
| Both expressions are empty | Empty string is returned |
Boolean values are converted to -1 for FALSE and 0 for TRUE.
See also variant_div(), variant_idiv().
注: 对于所有的变量算法函数，此函数的参数可以要么是 PHP 自身的类型（整型，字符串，浮点型，布尔型或者 NULL），要么是一个 COM，VARIANT 或 DOTNET 类的实例。PHP 自身类型将被转换为变量，使用与 VARIANT 类的构造函数中相同的规则。COM 和 DOTNET 对象将具有其默认属性的值，取得并作为变量值使用。
变量算法函数是 COM 库中与其名称接近的函数的封装。此类函数的更多信息请参考 MSDN 库。PHP 函数命名有少许不同，例如 PHP 中的 variant_add() 对应于 MSDN 文档中的 VarAdd()。