C++ Standard Library Function

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Header file names ending in .h are "old-style" header files that have been superseded by the C++ Standard Library header files.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>,
<list>,
<deque>,
<queue>,
<stack>,
<map>,
<set>,
<bitset>

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>,
<stdexcept>

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