Programming I - Fall 2024, Part 5 - Functions

Programming I - Fall 2024, Part 5 - Functions

• C++ programs can have functions besides main().
• A function is a set of statements performing a specific task.
• Complex problems can be broken down into smaller functions.
• A function prototype informs the compiler about the function's existence and type signatures.
• Functions can be called within main() or other functions.
• Function calls invoke a function's execution.
• Function definitions define how a function operates.
• Modular programming, compared to writing the whole solution in main(), allows multiple programmers to work simultaneously, decreasing development time and creating more readable programs.
• Predefined functions are grouped into libraries (e.g., cmath).
• sqrt(x) calculates the non-negative square root of x.
• pow(x, y) calculates x raised to the power of y.
• floor(x) returns the largest integer less than x.
• A void function doesn't return a value.
• Functions may not require any parameters.
• Scope determines where a variable is accessible within a program.
• Local variables are defined and accessible only within a specific function.
• Global variables are declared outside all functions and accessible from any function.
• Reference variables act as aliases to existing variables.

Passing Parameters

• C++ offers pass-by-value and pass-by-reference parameter passing methods in functions.
• Pass-by-value creates a copy of the actual parameter's value. Changes to the formal parameter within the function don't affect the original parameter.
• Pass-by-reference passes the memory address of the actual parameter. Changes to the formal parameter directly affect the original variable.

Example - Greatest Common Divisor (GCD)

• The gcd() function computes the GCD of two integers.
• Example input: 30, 75. Example output: 15. GCD is found by iterating until a common divisor is found.