C++ Loops: Applications and Usage

• CC-102 is the worktext in Programming 2

UNIT 1. LOOPS

• The unit covers loop or repetition structures and their elements.
• Increment and decrement operators, and creating programs using loops are examined.
• When writing C++ codes, the same statement or statements' block may need to be repeated.
• Repetition structure (looping) helps execute repetitive tasks without retyping code in C++.
• Iteration is another term for looping.

Elements of Looping

• If a loop is missing an element, it will not function properly.

Loop Control Variable (LCV)

• LCV holds the value that is compared to the loop's limit, which determines when it ends.
• The loop control variable must be initialized first before it can be used in the program.

Sentinel Value (SV)

• The sentinel value is the standard for comparing the loop control variable in order to evaluate to true or false.
• The decision to continue or stop looping is based on the comparison result.

Loop Update (LU)

• Changes the value of the loop control variable inside the loop.
• This change can occur through incrementing or decrementing.
• The increment operator (++) adds 1 to its operand.
• The decrement operator (--) subtracts 1 from its operand.
• Increment and decrement operators can precede (prefix) or follow (postfix) the loop control variable.
• With the prefix, it is done before evaluating the expression. With postfix, it is done after the expression.
• Increment and decrement are not only for adding or subtracting 1, but can be any value.
• Failure to alter the loop control variable results in an infinite loop.
• An infinite loop is a loop that never stops.

Empty Loops

• Loops that do nothing are called empty loops.
• This occurs when the comparison expression in a for or while loop evaluates to false on the first try.
• For a loop to be effective, the comparison expression must evaluate to true at least once.

Types of Loops

• for LOOP
• while LOOP
• do while LOOP
• nested LOOP

for LOOP

• The for loop is a repetition control structure that efficiently executes a loop a specific number of times.
• The syntax is: for (initialization; comparison expression; update) { statement(s); }
• The initialization of the loop control variable is executed once.
• The comparison expression is evaluated after initialization. If it evaluates to true, the body of the loop is executed and continues.
• If the comparison expression evaluates as false, the body stops and the flow of control jumps to the next line post loop }.
• After the loop, the flow of control jumps back up to the update.
• The update updates the loop control variable in a variety of ways, such as an increment, up to the sentinal value.

while LOOP

• The while loop form of loop executes repetitive tasks.
• In a while loop, the initialization of the loop control variable is typed before the structure of the loop.
• The loop update is placed inside the loop body.
• The syntax is: initialization; while(comparison expression) { statement(s); loop update; }.

Loop Update Using Prompt

• The loop continues until the user stops the execution of the loop.
• In each iteration, the program prompts the user to continue or stop the loop.
• A positive response executes the loop body, while a negative response stops it.

do while Loop

• The do while loop is another variant.
• Its comparison happens at the end of the structure, so the body of the loop is executed at least once.
• This guarantees one execution.
• In for and while loops, the comparison is before, meaning the loop will not be executed if it is false.
• The structure is: initialization; do { statement/s; loop update; } while (comparison expression);

Nested Loops

• A nested loop is a loop inside another loop, consisting of an outer and inner loop.
• The outer loop executes first. When its comparison evaluates to true, the outer loop body begins.
• The inner loop executes and when the comparison of the inner loop evaluates to true, the inner loops runs repeatedly until false.
• The inner loop terminates, then the rest of the lines inside the outer loop body are executed.
• Then, the outer loop is updated, and the process is repeated.
• The total iterations for nested loops is calculated as times outer loop executes times the inner loop executes (tLoop = o * i).

UNIT 2. ARRAYS

• An array is a series of elements with the same data type in adjoining memory locations.
• Elements can be individually referenced by adding an index to the array's identifier.
• An array declaration allows placement of multiple quizzes in memory and access via array name and index.
• The index represents the memory location of an element, with the first element at index [0].
• The syntax to declare arrays is: data_type array_name[number of elements];
• The number of elements must be a constant value.

Initializing Arrays

• Arrays can be initialized by entering a value in the declaration. -Arrays may not be initialized.
• You can initialize arrays by giving certain values when they are declared, which are typically enclosed in curly braces {}.
• The syntax for initializing an array is: dataType arrayName[no_of_elements] = {val1, val2,..., valn};
• If the number of values is less than the length of the array, the remaining elements have a default value of 0.
• The brackets of the array can be empty, in which case the compiler will assume its length to be equal to the number of values entered.

Array Values

• Assigning the value of an element in an array is like assigning the value of any regular variable.
• Example: array_name[index_no] = value;
• In C++, exceeding array index bounds is not caught during compilation, but an error occurs during runtime.
• Brackets have two roles: specifying the size when declared and specifying concrete array elements when they are being accessed.

Multidimensional Arrays

• A multidimensional array is an array of arrays, with a common type known as the bi-dimensional which exists as a table.
• To declare the multi-dimensional array use this syntax: int array_name[rows][cols];
• Multidimensional arrays are not limited to two indices.

UNIT 3. FUNCTIONS

• Functions are code modules/segments that carry out individual tasks.
• A function in C++ is a group of statements, given a name, and executable when called in the program.
• The syntax is: data_type function_name (parameter_1, ..., parameter_n){ statement_1; statement_2; ... ; statement_n; }.
• data_type is the data type of the value that will be returned by the function.
• function_name is the identifier by which the function can be called.
• parameters are optional and can be as many as needed.
• Parameters are a data type followed by an identifier, separated by a comma.
• The statements consist of the body of the function, enclosed in braces {}, specifying what the function actually does.
• This is different from calling a function, parameters allow the passing of information to the function that is local.

Void Functions

• void functions are functions which do not return a value but only print messages on the screen.
• In place of of a data type, void functions use the keyword "void."
• A void function performs a task and then control goes back to where called without passing data..

Function Overloading

• Function overloading is a feature of object-oriented programming (OOP) where two or more functions can have the same name but different parameters.
• Function Overloading occurs when a function name is overloaded with different jobs.
• In C++, two or more functions can have the same name if any of these conditions were met:
• the number of parameters is different; and
• the type of parameters passed is different based on its position.
• Overloaded functions may or may not have different return types.

Explore C++ loop structures, increment/decrement operators, and the differences between while and do-while loops. Learn about infinite loops and matching loop types with descriptions. Ideal for understanding fundamental programming concepts in C++.