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std::string in C++ STL (Standard Template Library)

String in C++ STL (Standard Template Library): In this article, we are going to see how we can use string as a default datatype?
Submitted by Radib Kar, on February 27, 2019

String as datatype

In C, we know string basically a character array terminated by \0. Thus to operate with the string we define character array. But in C++, standard library gives us the facility to use string as a basic data type like integer.

Example:

    Like we define and declare,
    int i=5;
    
    Same way, we can do for a string like,
    String s= "IncludeHelp";

Remember, a string variable (literal) need to be defined under "". 'a' is a character whereas "a" is a string.

Basic operation that can be performed on string

• Accessing string characters
• Returning string size
• Compare
• Concatenation

Header file needed:

    #include <string>
    Or
    #include <bits/stdc++.h>

C++ program to demonstrate example of std::string

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

int main(){
	string s;

	//reading & printing
	cout<<"Enter your string\n";
	cin>>s;
	cout<<"Sting you entered is: "<<s<<endl; 
	//printing size/length
	cout<<"length of the "<<s<<" is = "<<s.length()<<endl;

	//adding two strings
	string s1="Include";
	string s2="Help";
	cout<<"s1+s2: "<<s1+s2<<endl;

	//comparing
	if(s1==s2)
		cout<<s1<<" and "<<s2<<" are equal"<<endl;
	else
		cout<<s1<<" and "<<s2<<" are not equal"<<endl;

	//accessing characters
	cout<<"character at 0 index in "<<s<<" is = "<<s[0]<<endl;
	cout<<"character at 1 index in "<<s<<" is = "<<s[1]<<endl;
	cout<<"character at 5 index in "<<s<<" is = "<<s[5]<<endl;

	return 0;
}

Output

Enter your string
IncludeHelp
Sting you entered is: IncludeHelp
length of the IncludeHelp is = 11
s1+s2: IncludeHelp
Include and Help are not equal
character at 0 index in IncludeHelp is = I
character at 1 index in IncludeHelp is = n
character at 5 index in IncludeHelp is = d