Literals in C++

 In C++, literals are fixed values that are used directly in the code. They represent constant data. Here's a breakdown of the common types of literals in C++:

1. Integer Literals

• Represent whole numbers without any fractional part.
• Can be expressed in decimal (base 10), octal (base 8), or hexadecimal (base 16) forms.
  • Decimal: 123, -45, 0
  • Octal: 012 (starts with 0), 077
  • Hexadecimal: 0x1A (starts with 0x), 0xFF
• Can have suffixes to specify the integer type:
  • u or U: unsigned (e.g., 100u)
  • l or L: long (e.g., 100l)
  • ll or LL: long long (e.g., 100ll)

2. Floating-Point Literals

• Represent numbers with a fractional part or an exponent.
• Can be expressed in decimal or exponential form.
  • Decimal: 3.14, -0.001, 12.0
  • Exponential: 1.23e4 (1.23 * 10^4), -0.5E-2 (-0.5 * 10^-2)
• By default, floating-point literals are of type double.
• Can have suffixes to specify the floating-point type:
  • f or F: float (e.g., 3.14f)
  • l or L: long double (e.g., 3.14l)

3. Character Literals

• Represent single characters enclosed in single quotes.
  • 'A', 'z', '5', ' ' (space)
• Can also represent special characters using escape sequences:
  • '\n': newline
  • '\t': horizontal tab
  • '\\' backslash
  • '\'': single quote
  • '\"': double quote

4. String Literals

• Represent sequences of characters enclosed in double quotes.
  • "Hello, world!", "C++ programming"
• String literals are stored as null-terminated arrays of characters.
• Can contain escape sequences like character literals.

5. Boolean Literals

• Represent truth values.
• Two boolean literals:
  • true
  • false

6. Pointer Literals

• Represent memory addresses.
• The only pointer literal is:
  • nullptr (represents a null pointer)

Example:

C++

#include <iostream>

int main() {
    int age = 30;             // 30 is an integer literal
    double pi = 3.14159;      // 3.14159 is a floating-point literal
    char initial = 'J';       // 'J' is a character literal
    std::string name = "John Doe"; // "John Doe" is a string literal
    bool is_student = true;   // true is a boolean literal
    int* ptr = nullptr;       // nullptr is a pointer literal

    std::cout << "Age: " << age << std::endl;
    std::cout << "Pi: " << pi << std::endl;
    std::cout << "Initial: " << initial << std::endl;
    std::cout << "Name: " << name << std::endl;
    std::cout << "Is student: " << is_student << std::endl;

    return 0;
}

In this example, 30, 3.14159, 'J', "John Doe", true, and nullptr are all literals. They represent fixed values that are used directly in the code.