This chapter describes
built-in functions, which fall into three categories: numeric, string, and
gawk provides additional groups of
functions to work with values that represent time, do bit manipulation, sort
arrays, provide type information, and internationalize and localize
Besides the built-in functions,
has provisions for writing new functions that the rest of a program can use.
The second part of this chapter describes these
user-defined functions. Finally, we explore
indirect function calls, a
gawk-specific extension that
lets you determine at runtime what function is to be called.
Built-in functions are always available for
awk program to call. This section defines all the built-in functions in
awk; some of these are mentioned in other
sections but are summarized here for your convenience.
To call one of
functions, write the name of the function followed by arguments in
parentheses. For example, ‘
atan2(y + z,
1)’ is a call to the function
atan2() and has two arguments.
Whitespace is ignored between the built-in function name and the opening parenthesis, but nonetheless it is good practice to avoid using whitespace there. User-defined functions do not permit whitespace in this way, and it is easier to avoid mistakes by following a simple convention that always works—no whitespace after a function name.
Each built-in function accepts a certain number of arguments. In some ...