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Chapter Summary

This chapter introduces selection, the fundamental programming concept that allows programs to execute different code paths based on conditions. Selection is essential because real-world problems often require different actions depending on specific circumstances.

Key Concepts​

  • Boolean Expressions and Comparison Operators

    • Comparison operators: (==, !=, <, >, <=, >=) compare values and produce truthy or falsey results
    • Truthy and Falsey: In C, zero (0) is falsey; all other values are truthy
    • Common pitfall: Distinguish between assignment (=) and equivalence (==) operators

  • Logical Operators

    • And (&&): True only when both operands are true
    • Or (||): True when at least one operand is true
    • Not (!): Reverses the truth value of an expression

  • Control Structures

    • if/else statement: Executes one block if a condition is true, another if false
    • if/else if/else statement: Handles multiple mutually exclusive conditions in sequence
    • Independent conditions if/if/.../if: Use separate if statements when choices are not mutually exclusive

  • Practical Applications

    • Mutually exclusive conditions: When only one of several options can be true (e.g., age categories for transit fares)
    • Default values: Initialize variables with default values and modify them only when specific conditions are met
    • Independent conditions: When multiple options can be true simultaneously (e.g., adding toppings to a drink)
    • Testing if x is between a and b inclusive: x >= a && x <= b
    • Testing if x is outside of range from a and b: (x < a) || (x > b)