C++: Convert Int to Char Array [3 Methods]

Summary: In this programming tutorial, we will learn different ways to convert a number of type int into a char pointer or array in C++.

Method 1: Using to_string() and c_str()

In this method, we first convert the given number into a c++-string and then transform it into the char* type using the c_str() method.

#include <iostream>
using namespace std;

int main() {
    int number = 123456;

    //convert number to c++-string
    string s = to_string(number);
    //transform the string to char* using c_str()
    const char* nchar = s.c_str();

    cout << nchar;
    return 0;
}

The c_str() method returns a const char* pointer to an array that has the same values as the string object with an additional terminating null-character (‘\0‘).

Method 2: Using to_chars()

The to_chars() method defined in the <charconv> header file converts an integer or a floating-point number into a sequence of char.

#include <iostream>
#include <charconv>
using namespace std;

int main() {
    int number = 123456;
    
    //find the length of the number
    int length = to_string(number).length();
    //declare a char* pointer array of the same length
    char* nchar = new char[length];
    //convert int to char using the to_chars() method
    to_chars(nchar, nchar+length, number);
    
    cout << nchar;
    return 0;
}

The three parameters which we have passed to the to_chars(first, last, value) are :

• first – pointer to the beginning of the char*.
• last – pointer to the last of the char*.
• value – The integer to convert.

Method 3: Using Sprintf()

Unlike other methods, this method converts an integer to a char array.

In this method, we use the sprintf() method to format and write the given integer into the char array.

#include <iostream>
using namespace std;

int main() {
    int number = 1234567890;
    
    //find the length of the number
    int length = to_string(number).length();
    //declare a char array of size = length+1
    char nchar[length+1];
    //convert int to char using the sprintf() method
    sprintf(nchar, "%d", number);
    
    cout << nchar;
    return 0;
}

The three parameters which we have used in the sprintf(cstr, format, value) are:

• cstr – pointer to the char array where the resulting c-string will be stored.
• format – format specifier of the value.
• value – the integer to convert.

Related Topic: What is the difference between char* and char[] in C/C++?

These were the three ways using which we can convert an int to char array in C/C++ programming languages.