Convert Vector of chars to String in C++

Prerequisites: 

• Vector in C++
• Strings in C++

Here, we will discuss how to convert the vector of chars to std::string in C++. There are mainly 7 ways to convert Char Vector to String in C++ as follows:

1. Using string constructor
2. Using String Stream and iterator
3. Using String Stream and index
4. Using push_back() function
5. Using append() function
6. Using insert() function
7. Using copy() method

1. Using string constructor

Create a string and initialize it with a range-based constructor.

Syntax: 

string_name(container begin iterator, container end iterator);

Example:

C++

// C++ program to convert vector of chars
// into string using string constructor
#include <bits/stdc++.h>
using namespace std;

int main()
{
    // Initializing vector with A..E characters
    vector<char> vec = { 'A', 'B', 'C', 'D', 'E' };
    // string constructor used to convert the vector into string
    string str(vec.begin(), vec.end());

    cout << str << endl;

    return 0;
}

Output

ABCDE

2. Using String Stream and iterator

Create a stringstream, traverse the string through the iterator and add the element into the stringstream by dereferencing the iterator.

Syntax: 

stringstream_name << *iterator << delimiter;

Example:

C++

// C++ program to convert vector of chars
// into string using String Stream
// and iterator
#include <bits/stdc++.h>
#include <sstream>
using namespace std;

int main()
{
    // creating vector of characters
    vector<char> vec = { 'A', 'B', 'C', 'D', 'E' };
    // creating stringstream object
    stringstream ss;

    for (auto it = vec.begin(); it != vec.end(); it++) {
        ss << *it << " ";
    }
    // printing stringstream object
    cout << ss.str() << endl;

    return 0;
}

Output

A B C D E 

3. Using String Stream and index

Create a stringstream, traverse the string through the index and add the element into the stringstream.

Syntax: 

stringstream_name << element << delimiter;

Example:

C++

// C++ program to convert vector of chars
// into string using String Stream and index
#include <bits/stdc++.h>
#include <sstream>
using namespace std;

int main()
{
    // creating vector of char
    vector<char> vec = { 'A', 'B', 'C', 'D', 'E' };
    // string stream object
    stringstream ss;

    for (int i = 0; i < vec.size(); i++) {
        ss << vec[i] << " ";
    }
    // printing stringstream object
    cout << ss.str() << endl;

    return 0;
}

Output

A B C D E 

4. Using push_back() function

Create a string and push back characters one by one into that string through traversing into the container.

Syntax: 

string_name.push_back(character);

Example:

C++

// C++ program to convert vector of chars
// into string using push_back function
#include <bits/stdc++.h>
using namespace std;

int main()
{
    vector<char> v = { 'A', 'B', 'C', 'D', 'E' };

    string s;

    for (char c : v) {
        s.push_back(c);
        s.push_back(' ');
    }

    cout << s;

    return 0;
}

Output

A B C D E 

5. Using append() function

Create a string and append characters one by one into that string by traversing into the container.

Syntax: 

string_name.append(1, character);

Example:

C++

// C++ program to convert vector of chars
// into string Using append() function
#include <bits/stdc++.h>
using namespace std;

int main()
{
    vector<char> v = { 'A', 'B', 'C', 'D', 'E' };

    string s;

    for (char& c : v) {
        s.append(1, c);
        s.append(1, ' ');
    }

    cout << s;

    return 0;
}

Output

A B C D E 

6. Using insert() function

Create a string and insert characters one by one into that string by traversing into the container using proper indexing.

Syntax: 

string_name.insert(index, 1, character);

Example:

C++

// C++ program to convert vector of chars
// into string Using insert() function
#include <bits/stdc++.h>
using namespace std;

int main()
{
    // vector of characters
    vector<char> v = { 'A', 'B', 'C', 'D', 'E' };

    string s;

    //  Here we are iterating over the vector and inserting
    //  the characters at the position 2*i and 2*i+1.
    for (int i = 0; i < v.size(); i++) {
        s.insert(2 * i, 1, v[i]);
        s.insert(2 * i + 1, 1, ' ');
    }
    // printing string
    cout << s;

    return 0;
}

Output

A B C D E 

7. Using copy() method

Create a ostringstream and copy the container through ostream_iterator, container iterator range, and container.back().

Syntax: 

copy(begin iterator, end iterator-1, ostream iterator <Type> (ostringstream_name, delimiter);
ostringstream_name << container.back();

Example:

C++

// C++ program to convert vector of chars
// into string Using copy() method
#include <bits/stdc++.h>
using namespace std;

int main()
{
    // creating vector of characters
    vector<char> vec{ 'A', 'B', 'C', 'D', 'E' };

    // creating an ostringstream object
    ostringstream stream;

    if (!vec.empty()) {
        // using copy() method to copy the elements of the
        // vector to the ostringstream object
        copy(vec.begin(), vec.end() - 1,ostream_iterator<char>(stream, " "));
        // printing the string using the str() method of
        // ostrigstream object.
        stream << vec.back();
    }

    cout << stream.str() << endl;

    return 0;
}

Output

A B C D E