There are many well known C library functions, but here we list some
perhaps less well known ones that are useful. These may not be available
on all machines but often there are related functions or GNU equivalents.
For linear, binary, hash and tree searches:
lsearch(),
bsearch(),
hsearch(),
tsearch().
For queues:
insque(),
rmque().
For sorting:
qsort().
To parse command line options:
getopt(),
getsubopt().
For pattern matching, file patterns or regular expressions:
gmatch(),
regcmp(),
regex().
To walk a file tree:
ftw().
To make temporary files or filenames:
tmpfile(),
tmpnam().