COMPUTER SCIENCE 10TH – DETAILED QUESTION ANSWERS
CONTROL STRUCTURE
Chapter # 04
Q.1: What are control structures?
Ans:
CONTROL STRUCTURES / STATEMENTS
Control structures control the flow of execution in a program or function. Control structures are used to repeat any block of code, transfer control to a specific block of code, and make a choice by selection. There are three basic control structures in C++ programming:
- Selection / Decision Making Control Structure
- Loops / Iteration Control Structure
- Jumps
Q.2: Define selection or decision-making control structure and name its types.
Ans:
SELECTION / DECISION-MAKING CONTROL STRUCTURES / STATEMENTS
The selection control structure allows a number of conditions, which lead to a selection of one out of several alternatives. There are three types of selection control structures:
- If selection structure / statement
- If-else selection structure / statement
- Switch selection structure / statement
Q.3: Define if selection structure with syntax, flow diagram, and example.
Ans:
1. if SELECTION STATEMENT
An if statement is a conditional statement that tests a particular condition. Whenever that condition evaluates as true, it performs an action, but if it is not true, then the action is skipped.
SYNTAX:
cpp
if (condition) {
Statement(s);
}
FLOW DIAGRAM:
- A decision is made based on a condition:
- If True, the Statement(s) are executed.
- If False, it goes directly to the End IF.
if SELECTION STATEMENT EXAMPLE:
cpp
#include<iostream>
using namespace std;
int main() {
int num;
cout << "Enter an integer number: ";
cin >> num;
if (num > 0) {
cout << "You entered a positive integer: " << num << "\n";
}
return 0;
}
OUTPUT:
bash
Enter an integer number: 10
You entered a positive integer: 10
Q.4: Define nested if selection structure with syntax and example.
Ans:
NESTED if STATEMENT
A condition can be written as deeply as needed within the body of another statement. This is called a nested if statement.
SYNTAX:
The general syntax of a nested if statement is:
cpp
if (condition 1) {
if (condition 2) {
statements;
}
}
NESTED if STATEMENT EXAMPLE:
cpp
#include<iostream>
using namespace std;
int main() {
int exp, status;
cout << "Enter experience: ";
cin >> exp;
cout << "\nEnter status: ";
cin >> status;
if (exp >= 4) {
if (status >= 2) {
cout << "\nBonus Given to Employee" << "\n";
}
}
return 0;
}
OUTPUT:
mathematica
Enter experience: 6
Enter status: 3
Bonus Given to EmployeeQ.5: Define if-else selection structure with syntax, flow diagram, and example.
Ans:
if-else SELECTION STATEMENT
An if-else selection structure performs a certain action when the condition is true and a different action when the condition is false.
SYNTAX:
cpp
if (condition) {
statement(s);
} else {
statement(s);
}
Flow Diagram:
- If the condition is True, it executes the If Body.
- If the condition is False, it executes the Else Body.
- The program then continues to the statement just below the if-else structure.
if-else SELECTION STATEMENT EXAMPLE:
cpp
#include<iostream>
using namespace std;
int main() {
(Continued on the next page or image.)
int number;
cout << "Enter an integer: ";
cin >> number;
if (number >= 0) {
cout << "The number is a positive integer: " << number << "\n";
} else {
cout << "The number is a negative integer: " << number << "\n";
}
cout << "This line is always printed.";
return 0;
}
OUTPUT:
vbnet
Enter an integer: -5
The number is a negative integer: -5
This line is always printed.
Q.6: Define else-if selection structure with example.
Ans:
else-if SELECTION STATEMENT
Nested if-else statements test for multiple conditions by placing if-else statements inside if-else statements. When a condition is evaluated as true, the corresponding statements are executed, and the rest of the structure is skipped. This structure is also referred to as the if-else-if ladder.
else-if SELECTION STATEMENT EXAMPLE:
cpp
#include<iostream>
using namespace std;
int main() {
int per;
cout << "\nEnter your percentage: ";
cin >> per;
if (per >= 80) {
(Continued on the next page or image.)
cout << "Your grade is A+.";
} else if (per >= 70) {
cout << "Your grade is A.";
} else if (per >= 60) {
cout << "Your grade is B.";
} else if (per >= 50) {
cout << "Your grade is C.";
} else {
cout << "Failed.";
}
return 0;
}
OUTPUT:
csharp
Enter your percentage: 70
Your grade is A
Q.7: Define switch statement with syntax, flow diagram, and example.
Ans:
SWITCH STATEMENT
A switch statement is a control statement that allows selection of only one choice among many given choices. The expression in a switch evaluates to return an integer or character value, which is then compared to the values present in different cases. It executes the block of code that matches the case value. If there is no match, then the default block is executed (if present).
SYNTAX:
cpp
switch (variable) {
case constant 1:
(Continued on the next page or image.)
statement(s);
break;
}
case constant 2: {
statement(s);
break;
}
default: {
statement(s);
break;
}
}
FLOW DIAGRAM
- Switch (Conditional Expression)
- Checks Case Condition 1:
- If True, executes Statement 1 and break.
- If False, checks Case Condition 2.
- Checks Case Condition 2:
- If True, executes Statement 2 and break.
- If False, continues to the next case.
- Checks Case Condition n:
- If True, executes Statement n and break.
- If False, goes to the Default.
- Default:
- Executes Default Statement if no case matches.
After the switch case, control goes to the Statement just below Switch Case.
SWITCH STATEMENT EXAMPLE:
cpp
#include<iostream>
using namespace std;
int main() {
char op;
float num1, num2;
cout << "Enter an operator (+, -, *, /): ";
cin >> op;
cout << "Enter two numbers: " << "\n";
cin >> num1 >> num2;
switch (op) {
case '+':
cout << num1 << " + " << num2 << " = " << num1 + num2;
break;
case '-':
cout << num1 << " - " << num2 << " = " << num1 - num2;
break;
case '*':
cout << num1 << " * " << num2 << " = " << num1 * num2;
break;
case '/':
cout << num1 << " / " << num2 << " = " << num1 / num2;
break;
default:
cout << "Error! The operator is not correct";
}
return 0;
}
OUTPUT:
mathematica
Enter an operator: +
Enter two numbers:
10 15
10 + 15 = 25
Q.8: Write down the difference between if-else and switch statement.
DIFFERENCES BETWEEN if-else & SWITCH STATEMENT
if-else SWITCH If-else statement is used to select among two alternatives. The switch statement is used to select among multiple alternatives. If-else can have values based on constraints. Switch can have values based on user choice. Float, double, char, int and other data types can be used in if-else condition. Only int and char data types can be used in switch block. It is difficult to edit the if-else statement, if the nested if-else statement is used. It is easy to edit switch cases as they are recognized easily.
Q.9: What are loops or iteration and define its types?
LOOP / ITERATION CONTROL STRUCTURE
Iteration or loop in computer programming is a process wherein a set of instructions or structures are repeated in a sequence a specified number of times until a condition is true. When the set of instructions is executed again, it is called an iteration. A loop statement allows us to execute a statement or a group of statements multiple times.
C++ provides the following types of loops to handle looping requirements:
- for loop
- while loop
- do-while loop
Q.10: Describe for loop with syntax, flow diagram and example.
for LOOP
A for loop is a repetition or iteration control structure that repeats a statement or block of statements for a specified number of times. The for-loop statement includes the initialization of the counter, the condition, and the increment. The for loop is commonly used when the number of iterations is known.
SYNTAX
The general syntax of for loop is:
cpp
for (initialization; test condition; increment/decrement) {
// Statements
}
Flow Diagram:
The flow diagram illustrates the execution of the for loop:
Condition is checked:
- If true, the statement is executed, followed by increment/decrement.
- If false, the loop ends.
The process repeats until the condition is false.
for Loop Example:
cpp
#include<iostream>
using namespace std;
int main() {
int i;
for (i = 1; i <= 10; i++) {
cout << i << " ";
}
return 0;
}
OUTPUT:
1 2 3 4 5 6 7 8 9 10
Q.11: Describe while loop with syntax, flow diagram, and example.
Ans. While Loop
The while loop allows the programmer to specify that an action is to be repeated while some conditions remain true. It is used when the exact number of loop repetitions before the loop execution begins are not known.
Syntax:
vbnet
The general syntax of a while loop is:
while(condition)
{
statement(s);
}
Flow Diagram:
- Initialization
- Check condition:
- If true, execute the code inside the body of the while loop.
- If false, end the loop.
while Loop Example:
cpp
#include<iostream>
using namespace std;
int main() {
int i = 1;
while (i <= 10) {
cout << i << " ";
i++;
}
return 0;
}
Q.12: Describe do while loop with syntax, flow diagram, and example.
Ans. do while Loop
A do-while loop is similar to a while loop, except that a do-while loop is guaranteed to execute at least one time, even if the condition fails for the first time. Unlike for and while loops, which test the loop condition at the start of the loop, the do-while loop checks its condition at the end of the loop.
Syntax:
vbnet
The general syntax of a do-while loop is:
do {
statement(s);
} while(condition);
Flow Diagram:
- Initialization
- Execute Code Inside Body of While Loop
- Check condition:
- If true, go back to the code inside the loop.
- If false, end the loop.
do while Loop Example
cpp
#include<iostream>
using namespace std;
int main() {
int i = 1;
do {
cout << i << " ";
i++;
} while (i <= 10);
return 0;
}
OUTPUT
1 2 3 4 5 6 7 8 9 10
Q.13: Describe nested loop with example.
Ans. Nested Loops
When one for, while or do while loop is existed within another loop, they are said to be nested. The inside loop is completely repeated for each repetition of the outside loop.
Nested Loop Example
cpp
#include<iostream>
using namespace std;
int main() {
int row, column;
for (row = 1; row <= 5; row++) {
for (column = 1; column <= 3; column++) {
cout << " * ";
}
}
return 0;
}
OUTPUT
markdown
* * *
* * *
* * *
* * *
* * *
Q.14: Write down the differences between for, while, and do while loop.
for loop while loop do while loop 1. It is a pre-test loop because the condition is tested at the start of the loop. 1. It is a pre-test loop because the condition is tested at the start of the loop. 1. It is a post-test loop because the condition is tested at the end of the loop, which executes the loop at least once. 2. It is known as an entry-controlled loop. 2. It is known as an entry-controlled loop. 2. It is known as an exit-controlled loop. 3. If the condition is not true the first time, then the control will never enter the loop. 3. If the condition is not true the first time, then the control will never enter the loop. 3. Even if the condition is not true for the first time, the control will enter the loop at least once. 4. There is no semicolon after the condition in the syntax of the for loop. 4. There is no semicolon after the condition in the syntax of the while loop. 4. There is a semicolon after the condition in the syntax of the do while loop. 5. Initialization and updating are part of the syntax. 5. Initialization and updating are not part of the syntax. 5. Initialization and updating are not part of the syntax.
Q.15: What are jump statements?
Ans. Jump Statements
These statements change the normal execution of the program and jump over a specific part of the program.
Following are the jump statements used in C++:
break continue goto return exit() Q.16: Define break statement with example.
Ans. break STATEMENT
The break statement allows you to exit a loop or a switch statement from any point within its body, bypassing its normal termination expression. It can be used within any C++ structure.
break EXAMPLE
cpp
#include<iostream>
using namespace std;
int main()
{
int count;
for(count = 1; count <= 100; count++)
{
cout << count;
if(count == 10)
break;
}
return 0;
}
Q.17: Define continue statement with example.
Ans. continue STATEMENT
The continue statement is just the opposite of the break statement. Continue forces the next iteration of the loop to take place, skipping the remaining statements of its body.
continue EXAMPLE
cpp
#include<iostream>
using namespace std;
int main()cpp
{
int count;
for(count = 1; count <= 10; count++)
{
if(count == 5)
continue;
cout << count;
}
return 0;
}
Q.18: Define goto statement with Example.
Ans. goto STATEMENT
In C++ programming, the goto statement is used for altering the normal sequence of program execution by transferring control to some other parts of the program.
goto EXAMPLE
cpp
#include<iostream>
using namespace std;
int main()
{
float num, average, sum = 0.0;
int i, n;
cout << "Maximum number of inputs: ";
cin >> n;
for(i = 1; i <= n; i++)
{
cout << "Enter number " << i << ": ";
cin >> num;
if(num < 0.0)
{
// Control of the program moves to jump:
goto Jump;
}
sum += num;
}
Jump:
average = sum / (n);
cout << "\n Average =" << average;
return 0;
}
Q.19: Define return statement with syntax.
Ans. return STATEMENT
The return statement returns the flow of execution to the function from where it is called. This statement does not mandatorily need any conditional statements. As soon as the statement is executed, the flow of the program stops immediately and returns the control from where it was called.
SYNTAX
cpp
return (expression / value);
Q.20: Define exit() statement with Syntax.
Ans. exit() STATEMENT
The exit function, declared in <stdlib.h>, terminates a C++ program. The value supplied as an argument to exit is returned to the operating system as the program’s return code or exit code.
SYNTAX
cpp
void exit(int);
