10.8 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