Loop in C++: A Detailed Discussion with Examples

Loop in C++: A Detailed Discussion with Examples

21 May 2024
Beginner
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C++ Programming For Beginners

Loops in C ++: An Overview

Are you interested in programming but don't know where to start? Have you ever heard the term loop? Looping is one of the key concepts behind programming, and learning how to use loops in C++ can open up a new world of code. Gain the foundational skills from this C++ tutorial and move to the advanced C++ training that includes in-depth coverage of loops and other essential programming concepts.

What are loops in C++?

Loops are a block of code that executes itself until the specified condition becomes false. In this section, we will look in detail at the types of loops used in C++ programming.

What is the need for Looping Statements in C++?

We can give some uses of loops in C++:
  • Loops allow the user to execute the same set of statements repeatedly without writing the same code multiple times.
  • It saves time and effort and increases the efficiency.
  • It reduces the chance of getting errors during compilation.
  • Loop makes the code readable and easier to understand, especially when dealing with complex logic or large data sets.
  • It promotes code reusability.
  • Loops help traverse data structures like arrays or linked lists.

Read More - C++ Interview Questions Interview Questions for Freshers

Types of Loops in C++

There are three types of loops used in C++ programming:
  1. for loop
  2. while loop
  3. do while loop

In this article, we will look at the C++ for loop in detail. The other two loops will be covered subsequently after this.

1.) for loop in C++

A for loop is a control structure that enables a set of instructions to get executed for a specified number of iterations. It is an entry-controlled loop.
for loop in C++

Syntax

for(initialization; testcondition; updateExpression)
{ 
//code to be executed 
} 
  • Here, the initialization statement is executed first and only once.
  • The testcondition is checked, if false the loop terminates
  • If the testcondition is true, the body of the loop executes
  • The update expression gets updated
  • Again the testcondition is evaluated
  • The process repeats until the testcondition becomes false.

Example in C++ Compiler

// Program to print numbers from 1 to 10
#include <iostream>
using namespace std;
int main() {
 for (int i = 1; i <= 10; i++) {
 cout << i << endl;
 }
 return 0;
}
The above code prints the numbers from 1 to 10 using a for loop in C++.
  • We know it will take 10 iterations to print 10 numbers so, we have used the for loop.
  • i is initialized to 0.
  • The condition i<10 will be checked. It is true, therefore i+1 i.e. 1 gets printed.
  • Then i increments to 1 again the condition, i<10 is evaluated.
  • The process will repeat until i become 10.

Output

1
2
3
4
5
6
7
8
9
10

2.) Nested for loop in C++

It is any type of loop inside a for loop.
Nested for loop in C++

Example

#include <iostream>
using namespace std;
int main() {
 for (int i = 1; i <= 5; i++) {
 for (int j = 1; j <= i; j++) {
 cout << j << " ";
 }
 cout << endl;
 }
 return 0;
} 
  • This C++ code generates a pattern of numbers using nested loops.
  • The inner loop j iterates from 1 to the current value of i, printing numbers and spaces
  • The outer loop i iterates from 1 to 5, regulating the number of rows.
  • As a result, there is a pattern of numerals rising in each row, with a new line between each row.

Output

1 
1 2 
1 2 3 
1 2 3 4 
1 2 3 4 5 

3.) Infinite for loop in C++

An infinite for loop gets created if the for loop condition remains true, or if the programmer forgets to apply the test condition/terminating statement within the for loop statement.

Syntax

for(; ;) 
{ 
 // body of the for loop. 
} 

In the above syntax, there is no condition hence, this loop will execute infinite times.

Example

 #include <iostream>

int main() {
 for (;;) {
 std::cout << "Hello World" << std::endl;
 }

 return 0;
}
In the above code, we have run the for loop infinite times, so "Hello World" will be displayed infinitely.

Output

Hello World
Hello World
Hello World
Hello World
Hello World
... 

4.) for-each loop/ range-based for loop

This is a new kind of loop introduced in the C++11 version. It is used exclusively to traverse through elements in an array and vector.

Syntax

for (variableName : arrayName/vectorName) {
 // code block to be executed
}

Here, for every value in the array or vector, the for loop is executed and the value is assigned to the variable.

Example in C++ Editor

#include <iostream>
using namespace std;

int main() {
 int num[7] = {10, 20, 30, 40, 50, 60, 70};
 for (int i : num) {
 cout << i << "\n";
 }
 return 0;
}

Output

10
20
30
40
50
60
70
Summary
In this tutorial, we looked at the for loop in C++ programming. We also saw infinite and nested for loop. Finally, we also discussed the new concept of for-each loop. If you want to learn more about programming in C++, you can enrol in our C++ certification training or check out our website for tutorials on various topics.
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About Author
Shailendra Chauhan (Microsoft MVP, Founder & CEO at Scholarhat by DotNetTricks)

Shailendra Chauhan is the Founder and CEO at ScholarHat by DotNetTricks which is a brand when it comes to e-Learning. He provides training and consultation over an array of technologies like Cloud, .NET, Angular, React, Node, Microservices, Containers and Mobile Apps development. He has been awarded Microsoft MVP 8th time in a row (2016-2023). He has changed many lives with his writings and unique training programs. He has a number of most sought-after books to his name which has helped job aspirants in cracking tough interviews with ease.
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