CS1030

1
C Standard Library

• Includes derivatives of
• Standard C Library
• Standard Template Library
• Later in this course
• and a lot of history

2
Standard C Library

• The Development of the C Language Dennis
  Ritchie
• Summary of C (and Unix) History
• 1968 _at_ ATT-Bell Labs/GE - Multics
• 1970 1st Unix kernel running on DEC PDP-7
  PDP-11
• 1971 early C Language created derived from BCPL
  and B
• 1973 essentials of modern C complete Unix
  kernel rewritten in C
• 1978 first book on programming in C
• early 1980s Unix C distributed by ATT becomes
  widely popular
• 1983 ANSI committee on C formed
• 1989 C adopted as ANSI standard
• ANSI Standard C Library
• 1995 Library Standard extended to support
  Unicode (multinational characters)
• 1999 additional support (complex number
  libraries, bool data type,)
• C is quirky, flawed, and an enormous success
• - Ritchie

3
Standard C Library

• 24 individual header files you include
• These get compiled along with your source code in
  your .cpp files, and contain
• Function declarations
• Data type definitions (more on these later,
  maybe)
• Macros (defines e.g. M_PI)
• Actual implementation is separated into a
  corresponding library files
• Library files (.lib) are pulled in by the linker
• Standard C Library is tiny compared to Javas
  standard class libraries
• E.g. no support for graphics, networking)
• Other libraries (e.g. MFC, QT) needed
• Nearly always 3rd party (e.g. Microsoft,
  Trolltech)

4
ANSI Std C headers (1-6)(blue text the ones I
most commonly used)

• ltassert.hgt Contains the assert macro, used to
  assist with detecting logical errors and other
  types of bug in debugging versions of a program.
• ltcomplex.hgt A set of functions for manipulating
  complex numbers. (New with C99)
• ltctype.hgt This header file contains functions
  used to classify characters by their types or to
  convert between upper and lower case in a way
  that is independent of the used character set
  (typically ASCII, although implementations
  utilizing EBCDIC are also known).
• lterrno.hgt For testing error codes reported by
  library functions.
• ltfenv.hgt For controlling floating-point
  environment. (New with C99)
• ltfloat.hgt Contains defined constants specifying
  the implementation-specific properties of the
  floating-point library, such as the minimum
  difference between two different floating-point
  numbers (_EPSILON), the maximum number of digits
  of accuracy (_DIG) and the range of numbers which
  can be represented (_MIN, _MAX).

5
ANSI Std C headers (7-12)

• ltinttypes.hgt For precise conversion between
  integer types. (New with C99)
• ltiso646.hgt For programming in ISO 646 variant
  character sets. (New with NA1)
• ltlimits.hgt Contains defined constants specifying
  the implementation-specific properties of the
  integer types, such as the range of numbers which
  can be represented (_MIN, _MAX).
• ltlocale.hgt For setlocale() and related
  constants. This is used to choose an appropriate
  locale.
• ltmath.hgt For computing common mathematical
  functions
• ltsetjmp.hgt For executing nonlocal goto statements

6
ANSI Std C headers (13-18)

• ltsignal.hgt For controlling various exceptional
  conditions
• ltstdarg.hgt For accessing a varying number of
  arguments passed to functions.
• ltstdbool.hgt For a boolean data type. (New with
  C99)
• ltstdint.hgt For defining various integer types.
  (New with C99)
• ltstddef.hgt For defining several useful types and
  macros.
• ltstdio.hgt Provides the core input and output
  capabilities of the C language. This file
  includes the venerable printf function.

7
ANSI Std C headers (19-24)

• ltstdlib.hgt For performing a variety of
  operations, including conversion, pseudo-random
  numbers, memory allocation, process control,
  environment, signalling, searching, and sorting.
• ltstring.hgt For manipulating several kinds of
  strings.
• lttgmath.hgt For type-generic mathematical
  functions. (New with C99)
• lttime.hgt For converting between various time and
  date formats.
• ltwchar.hgt For manipulating wide streams and
  several kinds of strings using wide characters -
  key to supporting a range of languages. (New with
  NA1)
• ltwctype.hgt For classifying wide characters. (New
  with NA1)

8
ltassert.hgt

• void assert(int expression)
• Macro used for internal error detection. (Ignored
  if NDEBUG is defined where ltassert.hgt is
  included.) If expression equals zero, message
  printed on stderr and abort called to terminate
  execution.

9
ltctype.hgt (1)

• int isalnum(int c)
• isalpha(c) or isdigit(c)
• int isalpha(int c)
• isupper(c) or islower(c)
• int iscntrl(int c)
• is control character. In ASCII, control
  characters are 0x00 (NUL) to 0x1F (US), and 0x7F
  (DEL)
• int isdigit(int c)
• is decimal digit
• int isgraph(int c)
• is printing character other than space
• int islower(int c)
• is lower-case letter

10
ltctype.hgt (2)

• int isprint(int c)
• is printing character (including space). In
  ASCII, printing characters are 0x20 (' ') to 0x7E
  ('')
• int ispunct(int c)
• is printing character other than space, letter,
  digit
• int isspace(int c)
• is space, formfeed, newline, carriage return,
  tab, vertical tab
• int isupper(int c)
• is upper-case letter
• int isxdigit(int c)
• is hexadecimal digit
• int tolower(int c)
• return lower-case equivalent
• int toupper(int c)
• return upper-case equivalent

11
lterrno.hgt

• errno
• object to which certain library functions assign
  specific positive values on error
• EDOM
• code used for domain errors
• ERANGE
• code used for range errors
• Notes
• other implementation-defined error values are
  permitted
• to determine the value (if any) assigned to errno
  by a library function, a program should assign
  zero to errno immediately prior to the function
  call

12
ltmath.hgt (1)

• On domain error, implementation-defined value
  returned and errno set to EDOM. On range error,
  errno set to ERANGE and return value is HUGE_VAL
  with correct sign for overflow, or zero for
  underflow. Angles are in radians.
• HUGE_VAL
• magnitude returned (with correct sign) on
  overflow error
• double exp(double x)
• exponential of x
• double log(double x)
• natural logarithm of x
• double log10(double x)
• base-10 logarithm of x
• double pow(double x, double y)
• x raised to power y
• double sqrt(double x)
• square root of x

13
ltmath.hgt (2)

• double ceil(double x)
• smallest integer not less than x
• double floor(double x)
• largest integer not greater than x
• double fabs(double x)
• absolute value of x
• double ldexp(double x, int n)
• x times 2 to the power n
• double frexp(double x, int exp)
• if x non-zero, returns value, with absolute value
  in interval 1/2, 1), and assigns to exp integer
  such that product of return value and 2 raised to
  the power exp equals x if x zero, both return
  value and exp are zero
• double modf(double x, double ip)
• returns fractional part and assigns to ip
  integral part of x, both with same sign as x
• double fmod(double x, double y)
• if y non-zero, floating-point remainder of x/y,
  with same sign as x if y zero, result is
  implementation-defined

14
ltmath.hgt (3)

• double sin(double x)
• sine of x
• double cos(double x)
• cosine of x
• double tan(double x)
• tangent of x
• double asin(double x)
• arc-sine of x
• double acos(double x)
• arc-cosine of x
• double atan(double x)
• arc-tangent of x
• double atan2(double y, double x)
• arc-tangent of y/x
• double sinh(double x)
• hyperbolic sine of x
• double cosh(double x)
• hyperbolic cosine of x
• double tanh(double x)

15
ltstddef.hgt

• NULL
• Null pointer constant.
• offsetof(stype, m)
• Offset (in bytes) of member m from start of
  structure type stype.
• ptrdiff_t
• Type for objects declared to store result of
  subtracting pointers.
• size_t
• Type for objects declared to store result of
  sizeof operator.

16
ltstdlib.hgt

• ltstdlib.hgt
• EXIT_FAILURE
• Value for status argument to exit indicating
  failure.
• EXIT_SUCCESS
• Value for status argument to exit indicating
  success.
• RAND_MAX
• Maximum value returned by rand().
• NULL
• Null pointer constant.

17
ltstdlib.hgt

• void abort()
• Terminates program abnormally, by calling
  raise(SIGABRT).
• void exit(int status)
• Terminates program normally. Functions installed
  using atexit are called (in reverse order to that
  in which installed), open files are flushed, open
  streams are closed and control is returned to
  environment. status is returned to environment in
  implementation-dependent manner. Zero or
  EXIT_SUCCESS indicates successful termination and
  EXIT_FAILURE indicates unsuccessful termination.
  Implementations may define other values.
• int atexit(void (fcm)(void))
• Registers fcn to be called when program
  terminates normally (or when main returns).
  Returns non-zero on failure.
• int system(const char s)
• If s is not NULL, passes s to environment for
  execution, and returns status reported by command
  processor if s is NULL, non-zero returned if
  environment has a command processor.
• char getenv(const char name)
• Returns string associated with name name from
  implementation's environment, or NULL if no such
  string exists.

18
ltstdlib.hgt

• void bsearch(const void key, const void base,
  size_t n, size_t size, int (cmp)(const void
  keyval, const void datum))
• Searches ordered array base (of n objects each of
  size size) for item matching key according to
  comparison function cmp. cmp must return negative
  value if first argument is less than second, zero
  if equal and positive if greater. Items of base
  are assumed to be in ascending order (according
  to cmp). Returns a pointer to an item matching
  key, or NULL if none found.
• void qsort(void base, size_t n, size_t size, int
  (cmp)(const void, const void))
• Arranges into ascending order array base (of n
  objects each of size size) according to
  comparison function cmp. cmp must return negative
  value if first argument is less than second, zero
  if equal and positive if greater.
• int rand(void)
• Returns pseudo-random number in range 0 to
  RAND_MAX.
• void srand(unsigned int seed)
• Uses seed as seed for new sequence of
  pseudo-random numbers. Initial seed is 1.

19
ltstring.hgt

• A whole bunch of functions that deal with
  handling C-style strings (arrays of characters)
• Not the same as a C string
• Remember, C had no classes
• C programs should use the string class from the
  C Standard Library wherever possible.
• Not the same as the C ltstringgt include

20
lttime.hgt

• CLOCKS_PER_SEC
• The number of clock_t units per second.
• NULL
• Null pointer constant.
• clock_t
• An arithmetic type elapsed processor representing
  time.
• time_t
• An arithmetic type representing calendar time.

21
ltstdio.hgt

• ltstdio.hgt
• BUFSIZ
• Size of buffer used by setbuf.
• EOF
• Value used to indicate end-of-stream or to report
  an error.
• FILENAME_MAX
• Maximum length required for array of characters
  to hold a filename.
• FOPEN_MAX
• Maximum number of files which may be open
  simultaneously.
• L_tmpnam
• Number of characters required for temporary
  filename generated by tmpnam.
• NULL
• Null pointer constant.
• SEEK_CUR
• Value for origin argument to fseek specifying
  current file position.
• SEEK_END
• Value for origin argument to fseek specifying end
  of file.
• SEEK_SET
• Value for origin argument to fseek specifying
  beginning of file.

22
Standard book on the Standard C Library
23
Standard C Library within C Standard Libary

• Includes small modifications that make it easier
  to work with C
• Names of the Standard C Library header files
  changed from ltxxx.hgt to ltcxxxgt
• C-style names are still available, although
  deprecated
• include ltmath.hgtor
• include ltcmathgt // actually, cmath includes
  math.h
• All identifiers are part of the std namespace

24
C Standard Library

• A collection of classes and functions
• containers
• lists similar to Java LinkedList
• Vectors similar to Java ArrayList
• strings and streams
• interactive
• file I/O
• common functions for tasks such as finding the
  square root of a number (from the Standard C
  Librarys ltcmathgt rather than ltmath.hgt)
• 69 header files
• 19 of these are deprecated
• Still tiny compared to Javas standard class
  libraries

25
Containers similar to Java Collections Framework
classes

• ltbitsetgt
• ltdequegt
• ltlistgt
• ltmapgt
• ltqueuegt
• ltsetgt
• ltstackgt
• ltvectorgt

26
Streams and Input/Output

• ltfstreamgt
• ltiosgt
• ltiostreamgt // includes istream
• ltiosfwdgt
• ltiomanipgt
• ltistreamgt // includes ostream
• ltostreamgt
• ltsstreamgt
• ltstreambufgt

27
Strings

• demo