The C++ Standard Library provides a rich collection of functions for performing common mathematical calculations, string manipulations, character manipulations, input/output, error checking and many other useful operations. This makes the programmer's job easier, because these functions provide many of the capabilities programmers need. The C++ Standard Library functions are provided as part of the C++ programming environment.
Header file names ending in .h are "old-style" header files that have been superseded by the C++ Standard Library header files.
C++ Standard Library header file |
Explanation |
<iostream> |
Contains function prototypes for the C++ standard input and standard output functions. This header file replaces header file <iostream.h>. |
<iomanip> |
Contains function prototypes for stream manipulators that format streams of data. This header file replaces header file <iomanip.h>. |
<cmath> |
Contains function prototypes for math library functions. This header file replaces header file <math.h>. |
<cstdlib> |
Contains function prototypes for conversions of numbers to text, text to numbers, memory allocation, random numbers and various other utility functions. This header file replaces header file <stdlib.h>. |
<ctime> |
Contains function prototypes and types for manipulating the time and date. This header file replaces header file <time.h>. |
<cctype> |
Contains function prototypes for functions that test characters for certain properties (such as whether the character is a digit or a punctuation), and function prototypes for functions that can be used to convert lowercase letters to uppercase letters and vice versa. This header file replaces header file <ctype.h> |
<cstring> |
Contains function prototypes for C-style string-processing functions. This header file replaces header file <string.h>. |
<cstdio> |
Contains function prototypes for the C-style standard input/output library functions and information used by them. This header file replaces header file <stdio.h>. |
<fstream> |
Contains function prototypes for functions that perform input from files on disk and output to files on disk. This header file replaces header file <fstream.h>. |
<climits> |
Contains the integral size limits of the system. This header file replaces header file <limits.h>. |
<cassert> |
Contains macros for adding diagnostics that aid program debugging. This replaces header file <assert.h> from pre-standard C++. |
<cfloat> |
Contains the floating-point size limits of the system. This header file replaces header file <float.h>. |
<string> |
Contains the definition of class string from the C++ Standard Library |
<vector>, |
These header files contain classes that implement the C++ Standard Library containers. Containers store data during a program's execution. |
<typeinfo> |
Contains classes for runtime type identification (determining data types at execution time). |
<exception>, |
These header files contain classes that are used for exception handling. |
<memory> |
Contains classes and functions used by the C++ Standard Library to allocate memory to the C++ Standard Library containers. |
<sstream> |
Contains function prototypes for functions that perform input from strings in memory and output to strings in memory. |
<functional> |
Contains classes and functions used by C++ Standard Library algorithms. |
<iterator> |
Contains classes for accessing data in the C++ Standard Library containers. |
<algorithm> |
Contains functions for manipulating data in C++ Standard Library containers. |
<locale> |
Contains classes and functions normally used by stream processing to process data in the natural form for different languages (e.g., monetary formats, sorting strings, character presentation, etc.). |
<limits> |
Contains classes for defining the numerical data type limits on each computer platform. |
<utility> |
Contains classes and functions that are used by many C++ Standard Library header files. |
Mathematical Functions
Some of the important mathematical functions in header file <cmath> are
Function | Meaning |
sin(x) | Sine of an angle x (measured in radians) |
cos(x) | Cosine of an angle x (measured in radians) |
tan(x) | Tangent of an angle x (measured in radians) |
asin(x) | Sin-1 (x) where x (measured in radians) |
acos(x) | Cos-1 (x) where x (measured in radians) |
exp(x) | Exponential function of x (ex) |
log(x) | logarithm of x |
log 10(x) | Logarithm of number x to the base 10 |
sqrt(x) | Square root of x |
pow(x, y) | x raised to the power y |
abs(x) | Absolute value of integer number x |
fabs(x) | Absolute value of real number x |
Character Functions
All the character functions require <cctype> header file. The following table lists the function.
Function | Meaning |
isalpha(c) | It returns True if C is an uppercase letter and False if c is lowercase. |
isdigit(c) | It returns True if c is a digit (0 through 9) otherwise False. |
isalnum(c) | It returns True if c is a digit from 0 through 9 or an alphabetic character (either uppercase or lowercase) otherwise False. |
islower(c) | It returns True if C is a lowercase letter otherwise False. |
isupper(c) | It returns True if C is an uppercase letter otherwise False. |
toupper(c) | It converts c to uppercase letter. |
tolower(c) | It converts c to lowercase letter. |
Use of these functions are disscussed in assignment