Convert String to Char Array and Char Array to String in C++

C++ provides us with the following techniques to convert a string to char array:

• Using c_str() and strcpy() function
• Using a for loop

1. The c_str() and strcpy() function in C++

C++ c_str() function along with C++ String strcpy() function can be used to convert a string to char array easily.

The c_str() method represents the sequence of characters in an array of string followed by a null character (‘\0’). It returns a null pointer to the string.

Syntax:

string-name.c_str();

• At first, we use c_str() method to get all the characters of the string along with a terminating null character.
• Further, we declare an empty array of type char to store the result i.e. result of the conversion of string to char array.
• Finally, we use strcpy() method to copy the character sequence generated by the c_str() method to the empty char array.

Example:

#include <bits/stdc++.h> 
using namespace std; 

int main() 
{ 
	 
	string str = "";
	cout<<"Enter the string:\n";
	
	cin>>str;

	char arr[str.length() + 1]; 

	strcpy(arr, str.c_str()); 
    cout<<"String to char array conversion:\n";
	for (int i = 0; i < str.length(); i++) 
		cout << arr[i]; 

	return 0; 
} 

Output:

Enter the string:
JournalDev
String to char array conversion:
JournalDev

2. String to Char Array Conversion in C++ Using for Loop in

For the conversion of char array to a string, we can use C++ for loops with ease.

• Initially, we create an empty array of type char
• After this, we iterate through the input string
• While iterating, we store the characters into the char array

Example:

#include <bits/stdc++.h> 
using namespace std; 

int main() 
{ 
	 
	string str = "";
	cout<<"Enter the string:\n";
	
	cin>>str;

	char arr[str.length() + 1]; 
    cout<<"String to char array conversion:\n";
    for (int x = 0; x < sizeof(arr); x++) { 
        arr[x] = str[x]; 
        cout << arr[x]; 
    } 

	return 0; 
} 

Output:

Enter the string:
JournalDev
String to char array conversion:
JournalDev

The mentioned techniques can be used to convert a char array to string in C++:

• The ‘+’ operator
• C++ overloaded ‘=’ operator
• C++ inbuilt-constructor

1. C++ ‘+’ operator

C++ provides us with '+' operator to concatenate or add data items to a variable.

• We create a new empty string to store the result.
• Taking it ahead, we use a for loop to traverse through the input char array.
• In the process of traversing through the array, we use ‘+’ operator to concatenate the characters to the string.

Example:

#include <bits/stdc++.h> 
using namespace std; 


int main() 
{ 
	char arr[] = { 'J', 'O', 'U', 'R', 'N', 'A', 'L', 'D', 'E', 'V' }; 
	
	int size_arr = sizeof(arr) / sizeof(char); 
	string str = ""; 
	for (int x = 0; x < size_arr; x++) { 
		str = str + arr[x]; 
	} 
	cout<<"Converted char array to string:\n";
	cout << str << endl; 
	return 0; 
} 

Output:

Converted char array to string:
JOURNALDEV

2. C++ overloaded ‘=’ operator

C++ has got the concept of overloading which makes an operator perform other operations apart from the basic or default operation.

• Initially, we create a new empty string.
• We use the overloaded '=' operator to store the data items character by character into the newly created empty string.

Example:

#include <bits/stdc++.h> 
using namespace std; 


int main() 
{ 
	char arr[] = { 'J', 'O', 'U', 'R', 'N', 'A', 'L', 'D', 'E', 'V' }; 
	
	int size_arr = sizeof(arr) / sizeof(char); 
	string str = ""; 
	str = arr;
	cout<<"Converted char array to string:\n";
	cout << str << endl; 
	return 0; 
} 

Output:

Converted char array to string:
JOURNALDEV

3.C++ String inbuilt constructor

In the context of conversion of char array to string, we can use C++ String Constructor for the same.

Syntax:

string string-name(char array-name);

This constructor takes a sequence of characters terminated by a null character as an input parameter.

Note: This constructor string string() can be used only at the time of string declaration throughout the program.

Example:

#include <bits/stdc++.h> 
using namespace std; 

int main() 
{ 
	char arr[] = { 'J', 'O', 'U', 'R', 'N', 'A', 'L', 'D', 'E', 'V' }; 
	int size_arr = sizeof(arr) / sizeof(char); 
	string str(arr);
	cout<<"Converted char array to string:\n";
	cout <<str<< endl; 
	return 0; 
} 

Output:

Converted char array to string:
JOURNALDEV

In this article, we have understood various techniques to convert string to char array and vice-versa in C++.

• C++ c_str() method