http://www.phim.unibe.ch/comp_doc/c_manual/C/FUNCTIONS/funcref.htm
This is a summary of ANSI and POSIX functions grouped by library. If you want an alphabetical list, please use the master index. Please refer to a manual for a complete list of functions available to you.
Non Standard functions from CONIO.H
Non ANSI Standard Unix functions
Variable length argument lists.
ANSI standard library.The ANSI library is declared in the following header files. assert.h
POSIX libraryThe POSIX library contains the following headers.
ANSII Library headersassert.h
iscntrl Checks whether a character is a control character or delete ( decimal 0-31 and 127)
isdigit Checks whether a character is a digit (0-9)
isgraph Checks whether a character is a printable character, excluding the space (decimal 32)
islower Checks whether a character is a lower case letter (a-z).
isprint Checks whether a character is printable (decimal 32-126).
ispunct Checks whether a character is punctuation (decimal 32-47, 58-63, 91-96, 123-126)
isspace Checks whether a character is white space - space, CR HT VT NL, FF.
isupper Checks whether a character is an upper case letter (A-Z).
isxdigit Checks whether a character is hex digit (0-9, A-F, a-f).
toupper Converts a lowercase character to uppercase.
tolower Convert an uppercase character to lowercase. errno.h
math.h
ceil smallest integral value not less than x
cos Cosine.
fabs absolute value of floating-point number
floor largest integral value not greater than x
fmod floating-point remainder function
sin The sine of an integer.
tan Tangent.
tanh Hyperbolic tangent.
NoteFor some reason abs is in stdlib.h setjmp.h
longjmp signal.h
raise stdarg.h
See also vprintf vfprintf and vsprintf which all print the contents of a va_list stddef.hNo functions are declared in stddef.h. stdio.hThis header defines all the ANSI I/O functions that allow you to read and write to files and devices. Low level (non ANSI) functions are also available.
fclose Close a file.
feof Check for EOF while reading a file.
fgetc Read a character from a file.
fgets Read a record from a file (safer than fgetc).
fopen Open a file
fprintf O/P a line of data to a file.
fputc Put a charater into a file.
fputs Put a string into a file.
getc Get a character from an input stream.
getchar Get a character from the keyboard (STDIN).
gets Get string (from keyboard).
printf O/P data to the screen or a file.
putchar O/P a character to STDOUT.
puts O/P data to the screen or a file.
remove Remove a file.
sprintf O/P data in tha same way as 'printf' but put it into a string.
sscanf Extract fields from a string.
vfprintf O/P a va_list to a file.
vprintf O/P a va_list to stdout.
vsprintf O/P a va_list to a string. stdlib.h
abs compute the absolute value of an integer.
atexit Execute the named function when the program terminates.
atof convert a string to a double
atoi Accepts +-0123456789 leading blanks and converts to integer.
atol convert a string to a long integer
bsearch Binary chop.
calloc memory for an array.
div compute the quotient and remainder of integer division
exit Normally terminate a program.
getenv Get an environmental variable.
free memory allocated with malloc.
labs compute the absolute value of a long integer
ldiv compute the quotient and remainder of long integer division.
malloc dynamically allocate memory.
mblen determine the number of bytes in a character
mbstowcs convert a multibyte string to a wide character string.
mbtowc convert a multibyte character to a wide character
qsort Sort an array.
rand Generate a random number.
realloc Reallocate memory.
strtod Convert a string to a double.
strtol String to long integer conversion. Takes data in various number bases.
strtoul Convert a string to an unsigned long. This can also perform number base conversion.
srand Seed a random number.
system Issue a command to the operating system
wctomb convert a wide character to a multibyte character.
wcstombs convert a wide character string to a multibyte character string. string.h
memcmp Compare memory locations.
memcpy Copy memory.
memmove Move memory.
memset Set memory.
strcat Concatinate two strings.
strcmp Compare strings.
strcpy Copy strings.
strlen Length of a string.
strncat Concatinate two strings.
strncmp Compare two strings.
strncpy Copy part of a string.
strrchr Search for a character in a string.
strstr Search a string for a substring.
strtok The books say this function splits a string into tokens. I think its function is best described as parsing a string.
strxfrm time.h
Example program using some of the time functions.
POSIX functions start here....cpio.hdirent.h
closedir Close a directory.
readdir Read a directory entry.
rewinddir Return to the beginning of a directory.
scandir Scan a directory for a matching entry.
seekdir Move to an offset in a directory.
telldir Return the location within a directory. fcntl.hgrp.hpwd.hsys/stat.hsys/times.hsys/types.hsys/utsname.hsys/wait.htar.htermios.hunistd.hIt seems that this library contains headers for many functions that originally came with the ANSII standard library but did not have headers. My documentation for this POSIX library is incomplete.
chdir Change the current working directory.
chown Change the ownership of a file.
close Close a file (see low level functions)
chroot Change the root directory I am not 100% sure this is supposed to be in unistd.
dup duplicate a file descriptor
dup2 duplicate a file descriptor
fchdir Change the current working directory.I am not 100% sure this is supposed to be in unistd.
fork Create a child process.
fpathconf Change the current working directory.I am not 100% sure this is supposed to be in unistd.
getegid Get the group ID of the process.
geteuid Get the User ID of the process.
gethostname Name of the host (see uname). Not 100% sure this is in unistd
getopt, parse the command line Not 100% sure this is in unistd.
getgid Get a group ID.
getpid get process ID.
getppid, get parent process ID.
getuid Get the User ID of the process.
mkdir Make a directory
open Open a file
pause Put the program to sleep.
read Read a file descriptor.
rename Rename a file. This function can also be found in the ANSI stdio library. MAN PAGE.
rmdir Remove a directory
setgid Set the Group ID of the process.
unlink Remove a file
write Write to a file descriptor. utime.hconio.hDos Specific functions in conio.h Not very portable as conio.h is NOT in the ANSI standard library and does not appear on the Sun or Linux machines.
getch Get a character from the keyboard.
getche Get a character from the keyboard.
Non ANSI Standard Unix Functions.These functions are not in the ANSI standard libraries but are handy all the same.
statfs Filesystem statistics.
Ungrouped functions
