str_replace($search,$replace,$subject)：將$subject中的$search 都被$replace替換
此函數的入參可以是混合類型 mixed ,例如數組或字符串
返回值，返回一個字符串或數組。
例如：
//賦值：" <body text='black'> " "<body text='%body%'>"
str_replace("%body%","black","<body text='black'>");
//賦值： "Hll Wrld f PHP" "Hello World of PHP"
str_replace(array('a','e','i','o','u','A','E','I','O','U'),"","Hello World of PHP");
//賦值 ["Hello","World","of","PHP"] Array ( [0] => Hll [1] => Wrld [2] => f [3] => PHP )
str_replace(array('a','e','i','o','u','A','E','I','O','U'),"",["Hello","World","of","PHP"]);