Linux in a Nutshell, 6th Edition

User-Defined Functions

gawk allows you to define your own functions. This makes it easy to encapsulate sequences of steps that need to be repeated into a single place and reuse the code from anywhere in your program.

The following function capitalizes each word in a string. It has one parameter, named input, and five local variables, which are written as extra parameters:

# capitalize each word in a string
function capitalize(input, result, words, n, i, w)
{
   result = ""
   n = split(input, words, " ")
   for (i = 1; i <= n; i++) {
        w = words[i]
        w = toupper(substr(w, 1, 1)) substr(w, 2)
        if (i > 1)
                 result = result " "
        result = result w
   }
   return result
}

# main program, for testing
{ print capitalize($0) }

With this input data:

A test line with words and numbers like 12 on it.

This program produces:

A Test Line With Words And Numbers Like 12 On It.

Tip

For user-defined functions, no space is allowed between the function name and the left parenthesis when the function is called.