C Program to concatenate two strings into a third string without using built in functions

Program

#include<stdio.h>
void main()
{
	char str_one[20], str_two[20];
	char dest_str[40];
	int i, j;
	printf("Enter string one:\t");
	scanf(" %s", str_one);
	printf("Enter string two:\t");
	scanf(" %s", str_two);
	i = 0;
	while(str_one[i] != '\0')
	{
		dest_str[i] = str_one[i];
		i++;
	}
	j = 0;
	while(str_two[j] != '\0')
	{
		dest_str[i] = str_two[j];
		i++;
		j++;
	}
	dest_str[i] = '\0';
	printf("Concatenated string is: %s\n", dest_str);
}

Output

Enter string one:	United
Enter string two:	States
Concatenated string is: UnitedStates