A string is a sequence of bytes or characters, enclosed within either single quote (') or double quote (") characters. Examples:
'
"
字符串是是由零个或多个字符组成的有限序列，包裹在双引号””或者单引号’’里面。
'a string' "another string"
类型
大小
用途
STRING
2M
变长字符串
