How to use instr function in vb

How to use the instr function in vb

The function of the instr function is to find the first searched string starting from the starting position backwards If the position of the second occurrence is found, its position in the original string is returned, otherwise 0 is returned.

Syntax:

instr( string1, string2, start_position,nth_appearance )

Parameters:

string1: Source string, to be searched in this string.

string2: The string to be found in string1.

start_position: represents the position of string1 to start searching. This parameter is optional and defaults to 1 if omitted. String indexing starts at 1. If this parameter is positive, the search starts from left to right. If this parameter is negative, the search starts from right to left, and returns the starting index of the string to be found in the source string.

nth_appearance: Represents the number of occurrences of string 2 to be found. This parameter is optional. If omitted, the default is 1. If it is a negative number, the system will report an error.

Note:

The position index number starts from 1. If String2 is not found in String1, the instr function returns 0.

Example:

SELECT instr('syranmo','s') FROM dual; -- 返回 1
SELECT instr('syranmo','ra') FROM dual; -- 返回 3
SELECT instr('syran mo','at',1,2) FROM dual; -- 返回 0

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