Gawk/Library-Functions-Summary

Reading programs is an excellent way to learn Good Programming. The functions and programs provided in this chapter and the next are intended to serve that purpose.
When writing general-purpose library functions, put some thought into how to name any global variables so that they won’t conflict with variables from a user’s program.
The functions presented here fit into the following categories:
General problems

Number-to-string conversion, testing assertions, rounding, random number generation, converting characters to numbers, joining strings, getting easily usable time-of-day information, and reading a whole file in one shot

Managing data files

Noting data file boundaries, rereading the current file, checking for readable files, checking for zero-length files, and treating assignments as file names

Processing command-line options

An awk version of the standard C getopt() function

Reading the user and group databases

Two sets of routines that parallel the C library versions

Traversing arrays of arrays

Two functions that traverse an array of arrays to any depth