C++ Data Types and Structures

Chapter 10: Simple Data Types - Built-In and User-Defined

Overview of Data Types

• Data types in C++ categorize data into types, allowing for structured programming.
• C++ supports simple data types (built-in and user-defined) and structured data types.

Core Topics

• External and Internal Representations of Data: How data is viewed by the compiler versus how it's stored in memory.
• Integral and Floating Point Data Types: Different numeric types and their characteristics.
• Combined Assignment Operators: Simplifying arithmetic operations in variable assignments.
• Enumeration Types: Creating new data types using enumerations by listing potential values.
• User-Written Header Files: Including custom header files for data type definitions.

C++ Simple Data Types

• Integral Types: These include:
  • char (1 byte): Represents characters. Range: -128 to 127.
  • short (2 bytes): Range: -32,768 to 32,767.
  • int (typically 2 or 4 bytes): Range: -32,768 to 32,767.
  • long (4 bytes): Range: -2,147,483,648 to 2,147,483,647.
  • bool: Can be true or false.
• Floating Point Types:
  • float (4 bytes): Range: 3.4E-38 to 3.4E+38.
  • double (8 bytes): Range: 1.7E-308 to 1.7E+308.
  • long double (10 bytes): Extended range for high-precision requirements.

Key Points on Sizes and Ranges

• Size in bytes may be machine-dependent.
• Use the sizeof operator to determine the size of data types on the specific machine.
• C++ guarantees a basic size hierarchy.

Operators and Expressions

• Combined Assignment Operators:
  • age += 3; equivalent to age = age + 3;
  • Similar syntax for subtraction (-=), multiplication (*=), and division (/=) operations.

Enumeration Types

• Enumeration allows for defining a new data type with a set of named constants:

  enum MonthType { JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC };

• Declaring Enums: Create enumerated types in a clear and organized manner.
• Can be used in switch statements and comparisons using relational operators (e.g., <, >).

Structs and User-Defined Data Types

• A structured data type groups related data items together, allowing for access using a single name.
• Defining a Struct:

  struct AnimalType {
      long id;
      string name;
      ...
  };

• Access struct members using the dot operator (.).

Example Structs and Unions

• Struct Usage:
  • Access members via thisAnimal.name, thisAnimal.age++.
• Using Unions: Multiple data members but only one can be used at a time:

  union WeightType {
      long wtInOunces;
      int wtInPounds;
      float wtInTons;
  };

Pointers and References

• Pointer Variables: Hold memory addresses of variables.
• Use * to dereference a pointer and get its value. For example:

  int* ptr = &x;
  *ptr = 5;

• Reference Variables: Automatically manage memory addresses without needing explicit dereferencing:

  int& intRef = gamma;

Hierarchical Structures

• Struct members can be another struct type, enabling nesting and more complex data structures.
• Example:

  struct MachineRec {
      int idNumber;
      StatisticsType history;
  };

Conclusion

• Understanding simple and custom data types in C++ is crucial for efficient programming. Proper usage of structures, enums, and pointers enhances code clarity and organization, while ensuring effective data management.