C++ Tutorials

C++ - Do While Loop

Do-While Loop in C++

Introduction

The do-while loop in C++ is similar to the while loop, but with a key difference: it guarantees that the body of the loop is executed at least once, regardless of the condition. This is because the condition is evaluated after the loop's body is executed.

Syntax


do {
    // Code to be executed
} while (condition);

Explanation

  • do: Marks the start of the loop's body.
  • condition: The condition that is checked after the loop's body has been executed. If the condition evaluates to true, the loop continues; if false, the loop terminates.
  • The loop guarantees at least one execution of the loop body, even if the condition is false initially.

Example


#include 
using namespace std;

int main() {
    int count = 1;

    do {
        cout << "Count is: " << count << endl;
        count++;
    } while (count <= 5);

    return 0;
}

Output

The output will be:


Count is: 1
Count is: 2
Count is: 3
Count is: 4
Count is: 5

Advantages

  • The loop guarantees that the body is executed at least once, even if the condition is initially false.
  • Useful in scenarios where you need to execute code once before checking a condition (e.g., menu-driven programs, input validation).

Limitations

  • The condition is checked after the loop's body, meaning that the loop will always execute at least once.
  • It may not be suitable in cases where you want to check the condition before any execution.

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C++

Beginner 5 Hours

Do-While Loop in C++

Introduction

The do-while loop in C++ is similar to the while loop, but with a key difference: it guarantees that the body of the loop is executed at least once, regardless of the condition. This is because the condition is evaluated after the loop's body is executed.

Syntax


do {
    // Code to be executed
} while (condition);

Explanation

  • do: Marks the start of the loop's body.
  • condition: The condition that is checked after the loop's body has been executed. If the condition evaluates to true, the loop continues; if false, the loop terminates.
  • The loop guarantees at least one execution of the loop body, even if the condition is false initially.

Example


#include 
using namespace std;

int main() {
    int count = 1;

    do {
        cout << "Count is: " << count << endl;
        count++;
    } while (count <= 5);

    return 0;
}

Output

The output will be:


Count is: 1
Count is: 2
Count is: 3
Count is: 4
Count is: 5

Advantages

  • The loop guarantees that the body is executed at least once, even if the condition is initially false.
  • Useful in scenarios where you need to execute code once before checking a condition (e.g., menu-driven programs, input validation).

Limitations

  • The condition is checked after the loop's body, meaning that the loop will always execute at least once.
  • It may not be suitable in cases where you want to check the condition before any execution.

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Frequently Asked Questions for C++

A void pointer is a special type of pointer that can point to any data type, making it versatile for generic data handling.

Dynamic memory allocation in C++ refers to allocating memory at runtime using operators like new and delete, providing flexibility in memory management.

Templates in C++ allow functions and classes to operate with generic types, enabling code reusability and type safety.

Iterators are objects that allow traversal through the elements of a container in the STL, providing a uniform way to access elements.

C++ is an object-oriented programming language that extends C by adding features like classes, inheritance, and polymorphism. Unlike C, which is procedural, C++ supports both procedural and object-oriented paradigms.

An array in C++ is declared by specifying the type of its elements followed by the array name and size in square brackets, e.g., int arr[10];.

The new operator allocates memory dynamically on the heap, while the delete operator deallocates memory, preventing memory leaks.

Type casting in C++ is the process of converting a variable from one data type to another, either implicitly or explicitly.

Inheritance is a feature in C++ where a new class (derived class) acquires properties and behaviors (methods) from an existing class (base class).

Operator overloading enables the redefinition of the way operators work for user-defined types, allowing operators to be used with objects of those types.

Function overloading allows multiple functions with the same name but different parameters to coexist in a C++ program, enabling more intuitive function calls.

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No, a C++ program cannot execute without a main() function, as it is the designated entry point for program execution.

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A namespace in C++ is a declarative region that provides a scope to the identifiers (names of types, functions, variables) to avoid name conflicts.

The primary difference is that members of a struct are public by default, whereas members of a class are private by default.

The const keyword in C++ is used to define constants, indicating that the value of a variable cannot be changed after initialization.

Exception handling in C++ is a mechanism to handle runtime errors using try, catch, and throw blocks, allowing a program to continue execution after an error.

The STL is a collection of template classes and functions in C++ that provide general-purpose algorithms and data structures like vectors, lists, and maps.

A reference in C++ is an alias for another variable, whereas a pointer holds the memory address of a variable. References cannot be null and must be initialized upon declaration.

Pointers in C++ are variables that store memory addresses of other variables. They allow for dynamic memory allocation and efficient array handling.

Polymorphism allows objects of different classes to be treated as objects of a common base class, enabling a single function or operator to work in different ways.

Constructors are special member functions that initialize objects when they are created. Destructors are called when objects are destroyed, used to release resources.

These access specifiers define the accessibility of class members. Public members are accessible from outside the class, private members are not, and protected members are accessible within the class and by derived classes.

The main() function serves as the entry point for a C++ program. It is where the execution starts and ends.

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