length() 函数返回字符串的长度。
length()
n = String.length(string)
var a = String.length("");var b = String.length("Hello world");var c = String.length(23.4);
var a = String.length("");
var b = String.length("Hello world");
var c = String.length(23.4);
a = 0b = 11c = 4
a = 0
b = 11
c = 4