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Header file names ending in .h are "old-style" header files that have been superseded by the C++ Standard Library header files.

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