C++ Variables and Data Types

Variables

• A variable is a named storage location that holds a value.
• In C++, a variable must be declared before it can be used.
• A variable declaration consists of:
  • Data type (e.g., int, char, float)
  • Variable name (e.g., x, myVariable)
  • Optional initialization value (e.g., = 5, = "hello")

Data Types

Primitive Data Types

• Integers:
  • int: whole numbers (e.g., 1, 2, 3)
  • short: short integers (e.g., -32768 to 32767)
  • long: long integers (e.g., -2147483648 to 2147483647)
  • long long: extended long integers (e.g., -9223372036854775808 to 9223372036854775807)
• Floating-Point Numbers:
  • float: single-precision floating-point numbers (e.g., 3.14, -0.5)
  • double: double-precision floating-point numbers (e.g., 3.14159, -0.50000)
  • long double: extended-precision floating-point numbers
• Characters:
  • char: single character (e.g., 'a', 'Z', '?')
• Boolean:
  • bool: true or false values
• Void:
  • void: no value

Derived Data Types

• Arrays:
  • A collection of values of the same data type stored in contiguous memory locations.
  • Declared using the square bracket notation (e.g., int myArray[5];)
• Pointers:
  • A variable that holds the memory address of another variable.
  • Declared using the asterisk notation (e.g., int *ptr;)
• References:
  • An alias for an existing variable.
  • Declared using the ampersand notation (e.g., int &ref = x;)

Note: This is a basic overview of C++ variables and data types. There are more advanced topics and nuances to explore in each area.

Variables

• A variable is a named storage location that holds a value.
• Variables must be declared before they can be used.
• A variable declaration consists of a data type, variable name, and optional initialization value.

Data Types

Primitive Data Types

• Integers:
  • int: stores whole numbers (e.g., 1, 2, 3)
  • short: stores short integers (e.g., -32768 to 32767)
  • long: stores long integers (e.g., -2147483648 to 2147483647)
  • long long: stores extended long integers (e.g., -9223372036854775808 to 9223372036854775807)
• Floating-Point Numbers:
  • float: stores single-precision floating-point numbers (e.g., 3.14, -0.5)
  • double: stores double-precision floating-point numbers (e.g., 3.14159, -0.50000)
  • long double: stores extended-precision floating-point numbers
• Characters:
  • char: stores single characters (e.g., 'a', 'Z', '?')
• Boolean:
  • bool: stores true or false values
• Void:
  • void: represents no value

Derived Data Types

• Arrays:
  • A collection of values of the same data type stored in contiguous memory locations.
  • Declared using the square bracket notation (e.g., int myArray;).
• Pointers:
  • A variable that holds the memory address of another variable.
  • Declared using the asterisk notation (e.g., int *ptr;).
• References:
  • An alias for an existing variable.
  • Declared using the ampersand notation (e.g., int &ref = x;).

Variables

• A named storage location that holds a value.
• Must be declared before use.
• Declaration consists of data type, variable name, and optional initial value.

Data Types

Basic Data Types

• Integers:
  • int: whole numbers (e.g. 1, 2, 3, etc.).
  • short: short integer (e.g. -32768 to 32767).
  • long: long integer (e.g. -2147483648 to 2147483647).
  • long long: long long integer (e.g. -9223372036854775808 to 9223372036854775807).
• Floating Point Numbers:
  • float: single precision floating point (e.g. 3.14f).
  • double: double precision floating point (e.g. 3.14).
  • long double: extended precision floating point.
• Characters:
  • char: single character (e.g. 'a', 'B').
• Boolean:
  • bool: true or false value.

Derived Data Types

• Arrays: collection of values of the same data type.
• Pointers: variable that stores the memory address of another variable.
• References: alias for an existing variable.

Variable Initialization

• Can be initialized using the assignment operator (=).
• Can also be initialized using direct initialization (e.g. int x(5);) or uniform initialization (e.g. int x{5};).
• Good practice to initialize variables to avoid undefined behavior.