C++ Exercises: Concatenate three copies of each string in a given list of strings

Last update on August 13 2025 12:45:58 (UTC/GMT +8 hours)

Create List of Strings Each Repeated 3 Times

Write a C++ program to create a list from a given list of strings where each element is replaced by 3 copies of the string concatenated together.

Test Data:
Sample Input:
{ "1", "2", "3" , "4" }
Expected Output :
111 222 333 444

Sample Solution:

C++ Code :

#include <bits/stdc++.h>  // Include all standard C++ libraries
#include <list>  // Include the list container

using namespace std;  // Using standard namespace

// Function to create a new list where each element is replaced by three copies of the string concatenated together
list<string> test(list<string> nums) {
    list<string> new_list;  // Declare a new list to store modified elements
    list<string>::iterator it;  // Declare an iterator for traversing the input list 'nums'

    // Iterate through 'nums' list and concatenate three copies of each element together
    for (it = nums.begin(); it != nums.end(); ++it) {
        new_list.push_back(*it + *it + *it);  // Concatenate three copies of the string
    }

    return new_list;  // Return the new list with modified elements
}

// Function to display the elements of a list
display_list(list<string> g) {
    list<string>::iterator it;  // Declare an iterator for traversing the input list 'g'

    // Iterate through 'g' list and display each element
    for (it = g.begin(); it != g.end(); ++it) {
        cout << *it << ' ';  // Print each element followed by a space
    }
    cout << '\n';  // Move to a new line after displaying all elements
}

int main() {
    list<string> text = { "1", "2", "3", "4", "5", "6" };  // Initialize a list 'text' with strings
    cout << "Original list of elements:\n";
    display_list(text);  // Display the original list 'text'

    list<string> result_list;  // Declare a list to store the result of test() function
    result_list = test(text);  // Call the test() function to replace elements with three copies of the string
    cout << "\nNew list from the said list where each element is replaced\nby 3 copies of the string concatenated together:\n";
    display_list(result_list);  // Display the new list with modified elements

    return 0;  // Return 0 to indicate successful completion of the program
}

Sample Output:

Original list of elements:
1 2 3 4 5 6

New list from the said list where each element is replaced
by 3 copies of the string concatenated together:
111 222 333 444 555 666

Flowchart:

For more Practice: Solve these Related Problems:

Write a C++ program to generate a new array from a list of strings where each string is repeated three times consecutively.
Write a C++ program that reads an array of strings and outputs an array with each element concatenated with itself three times.
Write a C++ program to process a string array and replace every string with three copies of itself in succession.
Write a C++ program that takes an array of strings and prints each string repeated three times without any spaces in between.

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