index(lc($mystr), "a");.

If you want to look for $mysubstr instead of for "a", and you don't know that it's all lowercase, you'll need to apply lc to that as well, of course.

Originally posted as a Categorized Answer.

In reply to Re: How can I find the first position of a substring case-insensitively? by ariels
in thread How can I find the first position of a substring case-insensitively? by ChilliHead

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