How to Convert a char array to String in C++?

In this article, we will discuss different ways to convert a char array to a string in C++.

Table Of Contents

Problem Description

We have given an array that contains n charecters. Now, we have to convert this char array to a string.

Input

char arr[] = { 'p', 'o', 'i', 'n', 't', 'e', 'r' };

Output

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pointer

There are different ways to convert char array to string. Let’s discuss them one by one.

Convert char array to string using simple addition

In this approach, the array is iterated using for-loop and each element of the array is concatenated to form a resultant string. To do this, we can just use the ‘+’ operator to add element at the end of string.

Time Complexity: O(n)
Space Complexity: O(1)

#include <iostream>

using namespace std;

string convertArrayToString(char arr[], int n)
{
    // declaring an empty string
    string s = "";
    // iteration using for-loop
    for (int i = 0; i < n; i++)
    {
        // concatenation of string
        s += arr[i];
    }
    // return the string
    return s;
}

int main()
{
    char arr[] = { 'p', 'o', 'i', 'n', 't', 'e', 'r' };

    int n = sizeof(arr) / sizeof(arr[0]);

    // calling the function
    string s = convertArrayToString(arr, n);

    // print the resultant string
    cout << s << endl;
    return 0;
}

Output

pointer

In this example, we converted an array of characters to a string and printed it.

Convert char array to string using stringstream

In this approach, the concatenation of string is done using stringstream. The elements in the array are added in the string-stream and convertArrayToString() function returns the string-stream as a string.

Time Complexity: O(n)
Space Complexity: O(1)

#include <iostream>
#include <sstream>

using namespace std;

string convertArrayToString(char arr[], int n)
{
    // declaring an empty stringstream
    stringstream ss("");

    // iteration using for-loop
    for (int i = 0; i < n; i++) 
    {
        // putting the array elements in stringstream
        ss << arr[i];
    }

    // return the string
    return ss.str();
}

int main()
{
    char arr[] = { 'p', 'o', 'i', 'n', 't', 'e', 'r' };

    int n = sizeof(arr) / sizeof(arr[0]);

    // calling the function
    string s = convertArrayToString(arr, n);

    // print the resultant string
    cout << s << endl;

    return 0;
}

Output

pointer

In this example, we converted an array of characters to a string and printed it.

Convert char array to string using push_back() function

In this approach, the push_back() function is used for adding element to string. The elements of the array are pushed one by one in the string with the help of for-loop.

Time Complexity: O(n)
Space Complexity: O(1)

#include <iostream>

using namespace std;

string convertArrayToString(char arr[], int n)
{
    // declaring an empty string
    string str = "" ;

    // iteration using for-loop
    for (int i = 0 ; i < n ; i++ ) 
    {
        // concatenation of string
        str.push_back(arr[i]);
    }

    // return the string
    return str;
}

int main()
{
    char arr[] = { 'p', 'o', 'i', 'n', 't', 'e', 'r' };

    int n = sizeof(arr) / sizeof(arr[0]);

    // calling the function
    string s = convertArrayToString(arr, n);

    // print the resultant string
    cout << s << endl;

    return 0;
}

Output

pointer

In this example, we converted an array of characters to a string and printed it.

Summary

In this article we have seen various methods for converting a char array to a string. Happy Learning.

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