Strings in C++

July 20, 2023

Strings in C++

In C++, a string is a sequence of characters used to represent text. Strings are an essential part of programming as they allow us to work with textual data efficiently. Whether you’re dealing with user inputs, file manipulation, or any other text-based operations, understanding how to use strings in C++ is crucial.

Declaration,access and initialization of String in C++

A string is defined as an array of characterswith additional predefined methods support through headers

std::string ="value";

ex:

std::string name ="trishaank";//direct declaration and initialization
cout<<name;//directly access by string name

Advantages of Using Strings in C++:

Easy Manipulation: C++ strings provide a wide range of built-in functions that make it easy to manipulate and process textual data. Concatenation, searching, replacing, and other common string operations can be performed efficiently.

Dynamic Size: Unlike character arrays, C++ strings have a dynamic size. This means you don't need to worry about allocating an exact amount of memory for your string, as it can grow or shrink as needed.

Safer Operations: C++ strings handle memory allocation and deallocation automatically, reducing the risk of buffer overflow or memory leaks, which are common issues when working with character arrays.

Initialising at runtime

Run

#include 
using namespace std; 
int main()
{
string name;
cout<<"enter a name:"; cin>>name;
cout<<endl;
cout<<"given string is "<<name;
return 0;
}

Output:

enter a name:Anurag Sharma 

given string is Anurag

In the above example, we can see that the string is breaking after white space.to overcome this we use getline() method

getline()

It is used to accept a string of multiple words i.e it considers whitespace also a character in it
getline() function takes two parameters.
The first one is std::cin and the second one is the name of our string variable.

Run

#include <iostream>
using namespace std;
int main ()
{
  string name;
  cout << "\nenter a name:";
  getline (cin, name);		//reading a string
  cout << "\ngiven string is " << name;
  return 0;
}

Output:

enter a name:Anurag Sharma 

given string is Anurag Sharma

Concatenation operator(+)

We can directly join the strings using ‘+’ operator, hence it as an overloaded operator

Run

#include <iostream>
using namespace std;
int main(){
string s1="trish";
string s2="rish";
cout<<s1+s2<<endl;//trishrish
return 0;
}

Output

trishrish

length()

length() function returns the length of the string including whitespace characters.

Run

#include <iostream>
using namespace std;
int main()
{
string name; name = "My name is 3shaank";
cout << name.length() <<endl;//includes whitespaces also
return 0;
}

Output

Loop Types in C++

Decision Making in C++

Array in C++

String in C++

Function in C++

Printing only characters in between

Run

#include  <iostream>
using namespace std; 
int main() 
{ 
string str1 ("trishank"); 
cout << str1.substr(1,4) << endl;//charecters from 1 to 4 
return 0; 
}

Output

rish

Here, 4 characters starting from position 1 got printed.

find()

find() function finds the position of the first occurrence of a character

Run

#include <iostream>
 using namespace std;
 int main()
{ 
string str1 ("3sh");
cout << str1.find('s') << endl;//index of 's' 
return 0; 
}

Output

In this example, find() returned the position of ‘s’ in the string str1.

Find the position of a string in another string.

Run

#include <iostream>
using namespace std;
int main()
{
string str1 ("trishaank kumar");
string str2 ("kumar");
cout <<
str1.find(str2) <<endl; //start index of str2 in str 1
return 0;
}

Output

compare()

compare() function compares the value of a string ( str1 ) with another string ( str2 ).

It returns 0 if both the strings are equal.
It returns a positive value if either str1 > str2 or the first unmatched letter of str1 is greater than that of str2.
It returns a negative value if either str1 < str2 or the first unmatched letter of str1 is less than that of str2.

clear()

This function clears the data present strings and makes it empty.

Run

#include <iostream>
using namespace std;
int main()
{
string s = "I hate my college";
s.clear();//string became empty
cout << "Value of s is :" << s << endl;
cout<<"size of s"<<s.length();// 0 because empty
return 0;
}

Output

Value of s  is :
size :0

Example 1

Run

# include <iostream>
using namespace std;
int main()
{
string str1 ("trishaank");
string str2 ("trish");
cout << str1.compare(str2) << endl;
return 0;
}

Output:

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Strings in C++

Strings in C++

Declaration,access and initialization of String in C++

ex:

Advantages of Using Strings in C++:

Initialising at runtime

Output:

getline()

Output:

Concatenation operator(+)

Output

length()

Output

Printing only characters in between

Output

find()

Output

Find the position of a string in another string.

compare()

clear()

Output

Example 1

Output:

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