Constants/Literals in cpp

Welcome to the whimsical world of programming! In this module, we'll embark on an exciting journey to explore the magical realm of constants and literals in C++. Brace yourself as we unravel the secrets behind these mystical entities that play a pivotal role in maintaining fixed values within your programs. So, grab your coding wand and let's dive in!

A. Integer constants

Decimal constants : These are numbers expressed in the decimal (base 10) system.

int decimal = 10;

Octal constants : These are numbers expressed in the octal (base 8) system. They are preceded by a '0' (zero).

int octal = 012; // equivalent to decimal 10

Hexadecimal constants : These are numbers expressed in the hexadecimal (base 16) system. They are preceded by '0x' or '0X'.

int hexadecimal = 0x0A; // equivalent to decimal 10

B. Floating-point constants

These are numbers with fractional parts or numbers in scientific notation.

float floatingPoint = 3.14;
double doublePrecision = 2.71828;

C. Character constants

These are individual characters enclosed in single quotes.

char character = 'A';

D. String constants

These are sequences of characters enclosed in double quotes.

std::string str = "Hello, World!";

E. Boolean constants

These represent the truth values, either true or false.

bool trueValue = true;
bool falseValue = false;

F. Null constants

These represent a null or empty value.

int* pointer = nullptr;

Note : C++ also supports other types of constants like wide character constants, wide string constants, and user-defined literals, but the ones mentioned above are the most commonly used ones.

A. Naming conventions

• Constants are typically named using uppercase letters with underscores (_) separating words (e.g., MAX_VALUE).
• It's a good practice to use descriptive names that reflect the purpose of the constant.

B. Declaration and initialization

• Constants are declared using the 'const' keyword before the data type.
• Constants must be initialized at the time of declaration and cannot be modified afterward.
• The initialization can be done using an initializer list or an assignment operator (=).
• Constants can be declared globally (outside any function) or locally (inside a function or block).

Examples:

const int MAX_VALUE = 100; // globally declared constant
void function() {
    const float PI = 3.14159; // locally declared constant
    // You can use the constant in your code
    int result = MAX_VALUE * 2;
}

C. Constant qualifiers (const keyword)

• The 'const' keyword is used to declare a constant.
• It ensures that the value of the constant cannot be modified once it is initialized.
• Using 'const' helps improve code clarity and enables the compiler to optimize the program.

Note : Constants/literals in C++ are meant to represent fixed values that should not change during the execution of a program. Using constants enhances code readability, makes it easier to maintain and modify values, and provides compile-time checks for immutability.