Comparing a variable having an atomic value ( number, boolean, or string) to another such variable or a literal atomic value, and expecting the type of one to be cast automatically to the other type. 把包含原子值(数字、布尔值或字符串)的变量和另一个此类变量或者文字原子值比较,希望一种类型自动转换成另一种类型。