1. Computer & Information Sciences
University of Delaware
C++ Header Files and Standard Functions
(This info is taken from Appendix C of the nice book Data Abstraction and Problem Solving
with C++, 3rd ed., by F. M. Carrano& J.J. Prichard.)
Here is a list of commonly used C++ headers. If an older version of the header
exists, its name is shown in parentheses.
cassert (assert.h)
This library contains only the function assert. You use
assert(assertion);
to test the validity of an assertion. If assertion is false, assertwrites an error
message and terminates program execution. You can disable all occurrences
of assert in your program by placing the directive
#define NDEBUG
before the include directive.
cctype (ctype.h)
Most functions in this library classify a given ASCII character as a letter, a digit,
and so on. Two other functions convert letters between uppercase and lowercase.
The classification functions return a true value if ch belongs to the specified group;
otherwise they return false.
isalnum(ch)
Returns true if ch is either a letter or a decimal digit
isalpha(ch) Returns true if ch is a letter
iscntrl(ch) Returns true if ch is a control character (ASCII 127 or 0 to 31)
isdigit(ch) Returns true if ch is a decimal digit
isgraph(ch) Returns true if ch is printable and nonblank
islower(ch) Returns true if ch is a lowercase letter
isprint(ch) Returns true if ch is printable (including blank)
ispunct(ch) Returns true if ch is a punctuation character
Returns true if ch is a whitespace character: space, tab, carriage return, new
isspace(ch)
line, or form feed
isupper(ch) Returns true if ch is an uppercase letter
isxdigit(ch) Returns true if ch is a hexidecimal digit
toascii(ch) Returns ASCII code for ch
Returns the lowercase version of ch if ch is an uppercase letter; otherwise
tolower(ch)
returns ch
Returns the uppercase version of ch if ch is a lowercase letter; otherwise
toupper(ch)
returns ch

2. cfloat (float.h)
Defines named constants that specify the range of floating-point values.
climits (limits.h)
Defines named constants that specify the range of integer values.
cmath (math.h)
The C++ functions in this library compute certain standard mathematical functions.
These functions are overloaded to accomodate float, double, and long double.
Unless otherwise indicated, each function has one argument, with the return type
being the same as the argument type (either float, double, orlong double).
acos
Returns the arc cosine
asin Returns the arc sine
atan Returns the arc tangent
atan2 Returns the arc tangent x/y for arguments x and y
ceil Rounds up
cos
Returns the cosine
cosh Returns the arc cosine
exp
Returns ex
fabs Returns the absolute value
floor Rounds down
fmod Returns x modulo y for arguments x and y
frexp For arguments x and eptr, where x = m * 2e, returns m and sets eptr to point to e
ldexp Returns x * 2e , for arguments x and e
log
Returns the natural log
log10 Returns the log base 10
For arguments x and iptr, returns the fractional part of x and sets iptr to point to the
modf
integer part of x
pow
Returns xy , for arguments x and y
sin
Returns the sine
sinh Returns the hyperbolic sine
sqrt Returns the square root
tan
Returns the tangent
tanh Returns the hyperbolic tangent
cstdlib (stdlib.h)
abort
abs
atof
atoi
exit
rand()
Terminates program execution abnormally
Returns the absolute value of an integer
Converts a string argument to floating point
Converts a string argument to an integer
Terminates program execution
Generates an unsigned int between 0 and RAND_MAX, a named constant

3. defined in cstdlib header file
srand(unsigned n) Seeds the rand() function so that it generates different
sequences of random numbers. srand is often used in conjunction
with the time function from the ctime library. For example,
srand(time(0));
cstring (string.h)
This library enables you to manipulate C strings that end in the char '0', the null
char. Unless noted otherwise, these functions return a pointer to the resulting string
in addition to modifying an appropriate argument. The argument ch is a character,
n is an integer, and the other arguments are strings, which usually means they are
names of a char array, but can be string constants in some cases. For example,
strcmp("Hello", "Goodbye");
strcat(toS, fromS)
Copies fromS to the end of toS
strncat(toS, fromS, n) Copies at most n characters of fromS to the end
oftoS and appends 0
strcmp(str1, str2)
Returns an integer that is negative if str1 < str2,
zero if str1 == str2, and positive if str1 > str2
stricmp(str1, str2)
Behaves like strcmp, but ignores case
strncmp(str1, str2, n) Behaves like strcmp, but compares the first
n characters of each string
strcpy(toS, fromS)
Copies fromStoS
strncpy(toS, fromS, n) Copies n characters of fromS to toS, truncating
or padding with 0 as necessary
strspn(str1, str2)
Returns the number of initial consecutive
characters
of str1 that are not in str2
strcspn(str1, str2)
Returns the number of initial consecutive
characters
of str1 that are in str2
strlen(str)
Returns the length of str, excluding 0
strlwr(str)
Converts any uppercase letters in str to lowercase
without altering other characters
strupr(str)
Converts any lowercase letters in str to uppercase
without altering other characters
strchr(str, ch)
Returns a pointer to the first occurrence of ch
instr; otherwise returns NULL
strrchr(str, ch)
Returns a pointer to the last occurrence of ch in
str; otherwise returns NULL
strpbrk(str1, str2)
Returns a pointer to the first character in str1
that also appears in str2; otherwise returns NULL
strstr(str1, str2)
Returns a pointer to the first occurrence of str2
in str1; otherwise returns NULL
strtok(str1, str2)
Finds the next token in str1 that is followed by
str2, returns a pointer to the token and writes
NULL immediately after the token in str1
ctime
Defines functions for manipulating time and dates.
exception
Defines classes, types, and functions that relate to exception handling. A portion of
the class exception is shown below.

4. class exception
{
public:
exception() throw();
virtual -exception() throw();
exception&operator=(const exception %exc) throw();
virtualconst char *what() const throw();
}
fstream (fstream.h)
Declares the C++ classes that support file I/O.
iomanip (iomanip.h)
The manipulation in this library affect the format of steam operations. Note that
iostream contains additional manipulators.
setbase(b)
setfill(f)
setprecision(n)
setw(n)
Setts number base to b = 8, 10, or 16
Sets fill character to f
Sets floating-point precision to integer n
Sets field width to integer n
iostream (iostream.h)
The manipulators in this library affect the format of stream operations. Note that
iomanip contains additional manipulators.
dec
end1
ends
flush
hex
representation
oct
representation
ws
Tells subsequent operation to use decimal representation
Inserts new-line character n and flushes output stream
Inserts null character 0 in an output stream
Flushes an output stream
Tells subsequent I/O operations to use hexadecimal
Tells subsequent I/O operation to use octal
Extracts whitespace characters on input stream
string
This library enables you to manipulate C++ strings. Described here is a selection of
the functions that this library provides. In addition, you can use the following
operators with C++ strings: =, +, ==, !=, <, <=, >, >=, <<, and >>. Note that
positions within a string begin at 0.
erase()
erase(pos, len)
and
containslen characters
find(subString)
string
length()
Makes the string empty
Removes the substring that begins at position pos
Returns the position of a substring within the
Returns the number of characters in the string
(same as size)
replace(pos, len, str)
Replaces the substring that begins at position
pos and contains len characters with the string str
size()
Returns the number of characters in ths string
(same as length)
substr(pos, len)
Returns the substring that begins at position pos
and contains len characters