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Chapter Summary

This chapter introduces the fundamental concepts of how programs store and manipulate data. Understanding data types and memory is essential because all programs work with data, and the way that data is stored and interpreted determines what operations can be performed and what results will be produced.

Key Concepts​

  • Memory and Binary Representation

    • Bits and Bytes: A bit is the smallest unit of storage (0 or 1); a byte is 8 bits. The number of distinct values that can be stored in n bits is 2n2^n
    • Data Abstraction: All information in a computer is stored as binary numbers. Data types help us interpret those binary sequences (e.g., RGB values for colors, ASCII encoding for characters)

  • Data Types and Storage

    • Basic Types: char (1 byte), int (4 bytes), float (4 bytes), double (8 bytes)
    • Type Selection: Choose data types based on the range of values needed and the precision required
    • Modifiers: unsigned, short, and long modify the storage capacity and interpretation of integer types

  • Variables

    • Declaration: Use the syntax typename variablename; to reserve memory for data
    • Initialization: Assign initial values using the assignment operator to ensure variables have default values
    • Naming Conventions: Use descriptive, lower camelCase names that convey the variable's purpose

  • Type Conversions

    • Narrowing: Converting from larger to smaller types can cause data loss (e.g., float to int truncates decimal places)
    • Promoting: Converting from smaller to larger types is safe and happens automatically in mixed-type operations
    • Explicit Casting: Use the syntax (typename)expression to clearly indicate intentional type conversions

  • Interactive Input and Output

    • printf(): Outputs formatted data using format codes (%d for int, %f for float, %lf for double, %c for char) and modifiers for precision and field width
    • scanf(): Reads formatted input from the user; requires the address-of operator (&) when reading basic types to find the location of where in memory the input should be stored
    • Format Codes: Each data type has a corresponding format code; mismatches between format codes and data types produce incorrect results