Locating the first instance of a character

In our programs, the need to find the first occurrence of a character is not uncommon. For example, we may be parsing a large text file and need to break it up into sections, based on an instance of a character. To perform this action, the string command accepts the keyword first.

The syntax for the string command is as follows:

string first varString string index

When invoked with the first keyword, the string command will search for a character or a sequence of characters in the string. If no match is found, the command returns a -1. If an index is provided, the search is constrained to the match at (or after) that index within the string.

How to do it…

In the following example, we will locate the first instance of the character a within a string. Return values from the commands are provided for clarity. Enter the following command:

% string first a 123abc123abc
3

How it works…

As you can see, string has located the first instance of the character...