Control Structures: If Statement

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Questions and Answers

Which control structure allows a program to choose from alternative paths of execution?

  • Repetition statement
  • Compound statement
  • Simple statement
  • Selection statement (correct)

What is a key characteristic of a compound statement in the context of control structures?

  • It ends with a semicolon.
  • It can't be used within control structures.
  • It's grouped into a block enclosed in braces. (correct)
  • It consists of a single instruction.

Under what condition will the statement within an if statement be executed?

  • Always, regardless of the expression's value.
  • If the expression isn't a number
  • Only if the expression evaluates to true. (correct)
  • Only if the expression evaluates to false.

What is the primary purpose of the else keyword in an if-else statement?

<p>To specify a block of code to execute only IF the initial <code>if</code> condition is false. (C)</p> Signup and view all the answers

How does the conditional operator (?:) function?

<p>It takes three arguments. (D)</p> Signup and view all the answers

What is the role of the break keyword in a switch statement?

<p>To prevent 'fall-through' to the next case. (D)</p> Signup and view all the answers

What happens in a switch statement when the expression does not match any of the listed case constants?

<p>The optional <code>default</code> section is executed if provided. (B)</p> Signup and view all the answers

Which statement about repetition structures is correct?

<p>Repetition structures execute a sequence of statements until a condition is met. (C)</p> Signup and view all the answers

What are the two essential segments of a program loop?

<p>Body and control statement. (D)</p> Signup and view all the answers

What distinguishes an entry-controlled loop from an exit-controlled loop?

<p>Entry-controlled loops test the condition prior to loop execution. (C)</p> Signup and view all the answers

Which type of loop is guaranteed to execute its body at least once?

<p><code>do-while</code> loop (C)</p> Signup and view all the answers

Which of the following is NOT a requirement for a while loop control variable to execute correctly?

<p>Being declared as <code>constant</code> (D)</p> Signup and view all the answers

In a for loop, what is the purpose of the 'initialization' section?

<p>To declare and optionally initialize loop control variables; it executes only once. (C)</p> Signup and view all the answers

What happens to the flow of control in a for loop after the body of the loop is executed?

<p>It checks the condition to decide if the body of the loop is to be executed again. (A)</p> Signup and view all the answers

In the context of loop control, what is a counter-controlled loop?

<p>A loop that iterates a known number of times. (D)</p> Signup and view all the answers

What is the role of a 'sentinel value' in a sentinel-controlled loop?

<p>To indicate the end of data input, causing the loop to terminate. (D)</p> Signup and view all the answers

What happens when a return 0; statement is executed within a function?

<p>The program or function terminates at the point of execution. (A)</p> Signup and view all the answers

What is the purpose of the stdlib. header file when using the exit() function?

<p>It's required as it contains the declaration for <code>exit()</code> (D)</p> Signup and view all the answers

What effect does the break statement have on a loop's execution?

<p>Terminates the loop entirely. (B)</p> Signup and view all the answers

In the context of loops, what is the key difference between break and continue statements?

<p><code>break</code> exits the loop; <code>continue</code> skips an iteration. (C)</p> Signup and view all the answers

What action does the continue statement perform in a loop?

<p>It skips to the beginning of the loop's body for the next iteration. (B)</p> Signup and view all the answers

What are potential consequences of using an 'empty for loop' ( for (;;) ) without any control statements?

<p>It will create an infinite loop. (C)</p> Signup and view all the answers

What is a 'zero iteration loop'?

<p>A loop whose condition is never met, so it never executes. (A)</p> Signup and view all the answers

In the context of loops, what is a 'flag-controlled loop'?

<p>A loop that uses a boolean variable to control its execution. (D)</p> Signup and view all the answers

What is the defining characteristic of a 'nested loop'?

<p>A loop within another loop. (A)</p> Signup and view all the answers

In nested loops, how often does the outer loop change in relation to the inner loop?

<p>The outer loop changes only after the inner loop has finished all its iterations (B)</p> Signup and view all the answers

Which loop statement described below would be described as a pretest loop?

<p>while (C)</p> Signup and view all the answers

What is the proper syntax for a simple if statement?

<p>if (conditional expression) statement; (B)</p> Signup and view all the answers

What is the correct syntax for the conditional operator?

<p>( expression1) ? expression2 : expression3 (A)</p> Signup and view all the answers

According to the material provided, which is the correct syntax for a compound statement?

<p>{ statement1; statement2; } (D)</p> Signup and view all the answers

Which of the options below accurately lists selection statements?

<p>if, if-else, switch (B)</p> Signup and view all the answers

What should you include in your code to handle unexpected values in a switch statement?

<p>default (D)</p> Signup and view all the answers

In a while loop, what happens if the condition is never met?

<p>The statements inside the loop are skipped. (C)</p> Signup and view all the answers

In a for loop, which of the following is executed only one time?

<p>Initialization (D)</p> Signup and view all the answers

Which type of the loop is best suited when the number of iterations are known?

<p>For loop (B)</p> Signup and view all the answers

Which of the following is/are additional features of for loop?

<p>You can use expressions in the assignment statements of initialization and increment section. (A)</p> Signup and view all the answers

Flashcards

Simple Statement

A simple instruction that ends with a semicolon.

Compound Statement

Instructions grouped into a block enclosed in braces {}.

"if" statement

A control flow statement that executes a block of code only if a specified condition is true.

"if-else" statement

A control flow statement that first evaluates a condition; if true, it executes a block of code, otherwise, it executes another block of code.

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Conditional operator(?:)

A shorthand way of writing a simple if-else statement. It is a ternary operator that takes three operands.

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"switch" statement

A control statement that allows a variable to be tested for equality against a list of values.

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"break" statement

A statement that separates the execution of statements per labeled case in a switch statement.

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"default" section

An optional section in a switch statement that is executed if the expression does not match any of the listed constants.

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Repetition statements

A control flow statement that allows code to be executed repeatedly based on a given boolean condition.

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Body of the Loop

A segment with instructions that will be repeated.

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Control Statement

A part of a loop that checks the condition for the execution of the body the loop.

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Entry-controlled loop

A loop where the condition is tested before the loop body is executed.

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Exit-controlled Loop

A loop where the condition is tested after the loop body is executed.

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"while" loop

A repetition statement that executes a block of code as long as a condition is true.

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"do-while" loop

A repetition statement similar to a while loop, but the loop body is executed at least once.

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"for" loop

A repetition statement useful for executing a block of code a specific number of times.

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Initialization

The initialization section of a for loop is executed only once to declare loop control variables.

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Test-condition

The test-condition is evaluated before each iteration; the loop continues if the condition is true.

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Increment/Decrement

The step size of an for loop, evaluated after the body to determine more iterations are necessary.

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"break" statement

It stops the execution of a loop or switch statement and transfers control to the statement immediately following the loop or switch.

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"continue" statement

A statement that skips the current iteration of a loop and proceeds to the next iteration.

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Zero Iteration Loop

A loop that immediately terminates upon the first test.

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Flag-controlled Loop

A loop that continues as long as a flag variable is true.

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Nested Loop

A loop placed inside the body of another loop.

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Study Notes

  • Lecture on Control Structures
  • Engineering Pre-Major Year Collaborative (EPYC) Program, January 2022

Remember: Simple Statements

  • Simple statements are simple instructions that end with a semicolon
  • Example: statement1;

Remember: Compound Statements

  • Compound statements are several instructions grouped into a block enclosed in braces {}
  • Example:
{ 
 statement1;
 statement2; 
}

Selection Statements

  • Checks certain conditions before executing a set of statements
  • Provides the branching mechanism which allows a program to choose from alternatives
  • Can be in the form of an if statement, if-else statement, conditional operator (?:), or a switch statement.

If Statement

  • Used for single selection
  • The statement executes if and only if the expression evaluates to true

If Statement: Simple Statement Syntax

if (conditional expression)
 statement;

If Statement Example

#include <iostream>
using namespace std;

int main() {
 int hinum = 0;
 cout << "Please type in a number";
 cin >> hinum;

 if (hinum == 123)
  cout << "Correct";
 return 0;
}

If Statement: Compound Statements Syntax

if (conditional expression)
{
 statement1;  //first
 statement2;  //second
    .
 statementN;  //Nth
}

Compound Statement Example

#include <iostream>
using namespace std;

int main() {
 float fPrice;
 cout << “Enter the price:”;
 cin >> fPrice;
 if (fPrice >= 1000) {
  cout << “Expensive!\n”;
  cout << “Can't Afford!\n”;
 }
 return 0;
}

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