Type header file in c++ and its function

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Type header file in c++ and its function

  1. 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. 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. 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. 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

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