Power Automate 现阶段还不能使用上Power Fx，所以我们可以使用Azure Logicapp 中的functions
string中的常用的一些function如下：
ps: 如有问号则为optional选项
Combine two or more strings, and return the combined string
Concat可以把2个/2个以上的string结合到一起，并且返回一个结合之后的string
Function: concat('<text1>', '<text2>', ...)
Example: concat('Hello', 'World')
Output: Hello World
Check whether a string ends with a specific substring. Return true when the substring is found, or return false when not found. This function is not case-sensitive.
检查你的string是否是以特定的有个substring做结尾。 返回值为bool（true/false） 如果找到结束为substring则返回true， 未找到substring则返回false。 这个方法不是大小写敏感。
Function: endsWith('<text>', '<searchText>')
Example: endsWith('hello world', 'world')
Output: true
Return a number as a string that's based on the specified format.
基于特定的格式将一个number返回一个string
Function: formatNumber(<number>, <format>, <locale>?)
Example:
formatNumber(1234567890, '0,0.00', 'en-us')
formatNumber(17.35, 'C2')
Output:
1,234,567,890.00
$17.35
Generate a globally unique identifier (GUID) as a string, for example, "c2ecc88d-88c8-4096-912c-d6f2e2b138ce":
Function:
guid()
guid('<format>') ps: GUID的remark各代表什么
Example: guid('P')
Output: "(c2ecc88d-88c8-4096-912c-d6f2e2b138ce)"
Return the starting position or index value for a substring. This function is not case-sensitive, and indexes start with the number 0.
返回substring在string中的index 值。 这个function不是大小写敏感功能，index 开始数为0
Function: indexOf('<text>', '<searchText>')
Example: indexOf('hello world', 'world')
Output: 6
Return the starting position or index value for the last occurrence of a substring. This function is not case-sensitive, and indexes start with the number 0.
返回开始位置或者在string中出现的substring的index值。 非大小写敏感，index开始值为0
Function: lastIndexOf('<text>', '<searchText>')
如果text 值是空，则返回-1
如果text和searchText两者皆为空，则返回0
如果searchText是空，则text的总长度减1
Example:
lastIndexOf('hello world hello world', 'world')
lastIndexOf('hello world hello world', '')
Output:
18
22
Return the number of items in a collection.
返回在一个string中所有字节总和
Function: length('<collection>')
Example: length('abcd')
Output: 4
Replace a substring with the specified string, and return the result string. This function is case-sensitive.
在string中把一部分旧字段用新字段代替掉。 大小写敏感功能
Function: replace('<text>', '<oldText>', '<newText>')
Example: replace('the old string', 'old', 'new')
Output: the new string
Return an array that contains substrings, separated by commas, based on the specified delimiter character in the original string.
把string中的所有字段按照指定的方式分割开，并且输出为array
Function: split('<text>', '<delimiter>')
Example: split('a_b_c', '_')
Output: ["a","b","c"]
Check whether a string starts with a specific substring. Return true when the substring is found, or return false when not found. This function is not case-sensitive.
检查string中是否以substring作为开始， 返回值为bool（true/false）, 非大小写敏感
Function: startsWith('<text>', '<searchText>')
Example: startsWith('hello world', 'hello')
Output: true
Return characters from a string, starting from the specified position, or index. Index values start with the number 0.
从string中，按照指定的index和长度返回相应的字段。 index值从0开始
Function: substring('<text>', <startIndex>, <length>)
Example: substring('hello world', 6, 5)
Output: world
Return a string in lowercase format. If a character in the string doesn't have a lowercase version, that character stays unchanged in the returned string.
把string中的所有字符改为小写
Function: toLower('<text>')
Example: toLower('Hello World')
Output: hello world
Return a string in uppercase format. If a character in the string doesn't have an uppercase version, that character stays unchanged in the returned string.
把string中的所有字符改为大写
Function: toUpper('<text>')
Example: toUpper('Hello World')
Output: HELLO WORLD
Remove leading and trailing whitespace from a string, and return the updated string.
Function: trim('<text>')
Example: trim(' Hello World ')
Output: Hello World