C - C++ Header Files and Standard Functions

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, assert writes 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.
isspace(ch)	Returns true if ch is a whitespace character: space, tab, carriage return, new 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.
tolower(ch)	Returns the lowercase version of ch if ch is an uppercase letter; otherwise returns ch.
toupper(ch)	Returns the uppercase version of ch if ch is a lowercase letter; otherwise returns ch.

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 accommodate 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, or long 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.
modf	For arguments x and iptr, returns the fractional part of x and sets iptr to point to the 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	Terminates program execution abnormally.
abs	Returns the absolute value of an integer.
atof	Converts a string argument to floating point.
atoi	Converts a string argument to an integer.
exit	Terminates program execution.
rand()	Generates an unsigned int between 0 and RAND_MAX, a named constant 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 of toS 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 fromS toS.
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 in str; 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.

     class exception
     {
     public:
        exception() throw();
        virtual -exception() throw();
        exception &operator=(const exception %exc) throw();
        virtual const 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)	Sets number base to b = 8, 10, or 16.
setfill(f)	Sets fill character to f.
setprecision(n)	Sets floating-point precision to integer n.
setw(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	Tells subsequent operation to use decimal representation.
end1	Inserts new-line character \n and flushes output stream.
ends	Inserts null character \0 in an output stream.
flush	Flushes an output stream.
hex	Tells subsequent I/O operations to use hexadecimal representation.
oct	Tells subsequent I/O operation to use octal representation.
ws	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()	Makes the string empty.
erase(pos, len)	Removes the substring that begins at position pos and contains len characters.
find(subString)	Returns the position of a substring within the string.
length()	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.

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