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What is String?

String is a nothing but a sequence of characters which is created by using a char array in C++ language. As a string in C++ is constructed by using a char array, hence the characters making up a string are stored in contagious memory locations(just like elements of any type of an array).

How a String is created in C++?

In C++, a string is nothing but a char array and it can be constructed in various ways, some are explained below -:

• First approach to create a string in C++
  
  

  // First approach to create a string in C++ 
  
  #include<iostream>
  
  int main()
  {
  	char arr[] = {'W', 'e', 'l', 'c', 'o', 'm', 'e', '\0'};
  }


This line of code creates a new char array i.e. a string with multiple characters which makes a single word, Welcome. A string always ends with a '\0' character, also known as the null character. When we create a string by using this approach, we must manually end it with a '\0' character .



• Second approach to create a string in C++
  
  

  // Another approach to create a string in C++ 
  
  #include<iostream>
  
  int main()
  {
  	char arr[] = "Welcome"; // no need to end this string with \0
  }
  


This code creates a string by using a char array and initializes it with a value, Welcome. When we create a string by using this approach, we don't have to manually insert a '\0' character at its end, as it is automatically inserted by the compiler when we press the Enter key.




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Creating multi-word strings in C++


In C++, we could even create a multi-word strings by using either of two explained approaches to create a string.



// Creating multi-word strings in C++

#include<iostream>

int main()
{

	/* creating a multi-word string - Hello there */
	char arr1[] = "Hello there"; 

	
	/* creating a  multi-word string - How are you? */	
	char arr2[] = "How are you?";	

	/* creating a multi-word string - Hi there */
	char arr3[] = {'H', 'i', ' ', 't', 'h', 'e', 'r', 'e'. '\0'};

	return 0;
}


This example creates three multi-word strings in the memory by following the two already explained ways to create a string by using a char array.






Printing a string in C++


Just as we can create a string in multiple ways, we can print a string in multiple ways, let us discuss some of these ways with a program.



• Using for loop to print a string in C++
  
  

  // Using for loop to print a string a string in C++
  
  #include<iostream>
  
  using namespace std;
  
  int main()
  {
  
  	// Creating a multi-word string i.e. Hello World 
  	char arr[] = {'H', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd', '\0'}; 
  
  	for(int i=0;i<11; i++)
  	{
  		cout<<arr[i]; // printing each character in string/char array using index
  	}
  	
  	return 0;
  }





Output

Hello World



This line of code creates a new char array i.e. string which is multi-word i.e. Hello World. The total number of characters in this multi-word string are 11, by including the space between Hello and World, and by excluding the '\0', null character.





In the diagram above, we have displayed how a c-style string is stored in contagious memory locations, starting with a memory address like 0x20000(hexadecimal form of memory address).

We have used a for loop to loop across the char array, by reading it characters starting at its index 0 until its last index 10(excluding the null character), which prints the multi-word string Hello World.






• Using while loop to print a string in C++
  
  

  /* Using while loop to print a string a string in C++ */ 
  
  #include<iostream>
  
  using namespace std;
  
  int main()
  {
  
  	/* Creating a multi-word string i.e. Hello World */
  	char arr[] = "Hello World"; 
  
  	int i=0;
  	while(i<11)
  	{
  		cout<<arr[i]; // printing each character in string/char array using index 
  		i++;
  	}
  	
  	return 0;
  }





Output

Hello World


Our last example also creates a new char array i.e. a string which is multi-word i.e. Hello World. Here, we have used a while loop to loop across a char array by reading it characters, starting at its index 0 until its last index 10(excluding the null character), which prints the multi-word string Hello World

In the next few tutorials, we are going to discuss some of the most important functions given to us by C++ to perform string manipulations.






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