INSTR
From QB64 Wiki
The INSTR function searches for the first occurance of a search STRING within a string and returns the position it was found.
- position% = INSTR([start%,] basestring$, searchstring$)
- The basestring position of the first character of the searchstring is returned by the function if found.
- Position returned will be 0 if the search found no matches in the base string.
- Start INTEGER position is optional. Must be at least 1 (start of a string) when used or an Illegal function call will occur.
- The Start position is useful when making multiple searches in the same string. Otherwise it starts at the beginning again!
- Base string and search string are any literal or variable STRING values.
- The search string should be smaller than the base string!
- Non-zero position return values can be used as a new start position by adding 1 to re-search the base string.
- In a loop, INSTR can search an entire file for occurences of certain words. See the MID$ statement example.
Example: Reading more than one instance of a word in a string using the INSTR return value as the start value plus 1.
text$ = "The cats and dogs where playing, even though dogs don't like cats." DO findcats% = INSTR(findcats% + 1, text$, "cats") ' find another occurance after IF findcats% THEN PRINT "There is 'cats' in the string at position:"; findcats% LOOP UNTIL findcats% = 0 findmonkey% = INSTR(text$, "monkeys") ' find any occurance? PRINT findmonkey%; "'monkeys' were found so it returned:"; findmonkey%
There is 'cats' in the string at position: 5 There is 'cats' in the string at position: 62 0 'monkeys' were found so INSTR returned: 0
- Explanation: When the INSTR return value is 0 there are no more instances of a string in a string so the search loop is exited.
See also: