The built-in string functions are much more significant as AWK is primarily designed as a string-processing language. These functions enhance AWK's power and functionality. In this section, we will discuss the following functions in detail:

• index (str, sub)
• length (string)
• split (str, arr, regex)
• substr (str, start, [ length ])
• sub (regex, replacement, string)
• gsub (regex, replacement, string)
• gensub (regex, replacement, occurrence, [ string ])
• match (string, regex)
• tolower (string)
• toupper (string)
• sprintf (format, expression)
• strtonum (string)