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In this tutorial we are going to discuss some important functions of string class with coding examples. So, let's get going.

• insert() function


This function inserts a string at a specified location in the called string.



// The insert() function in string class.

#include<iostream>
#include<string>

using namespace std;

int main()
{
string str("Hello");
cout<<"The string is : " << str <<"\n";

//Calling insert() function to insert a string into another string.
str.insert(2, "zzz");

cout<<"The modified string : " << str;
}





Output




The string is : Hello,
The modified string : Hezzzllo








• append() function


This method appends one string at the end of another string.



// The append() function in string class.

#include<iostream>
#include<string>

using namespace std;

int main()
{
string str("Hello,");
cout<<"The string is : " << str <<"\n";
string str2("how are you doing?");

//Calling append() function which appends only part of a string to the end of another string.
str.append(str2, 0, 10);
cout<<"The modified string after calling append() function : " << str;
}





Output




The string is : Hello
The modified string : Hezzzllo








• erase() function


This function erases a single or multiple character starting at a specified location within the called string.



// The erase() function in string class.

#include<iostream>
#include<string>

using namespace std;

int main()
{
string str("Welcome");
cout<<"The string is : " << str <<"\n";

//Calling erase() function to erase 2 characters starting from index 3
str.erase(3,2);
cout<<"The modified string after calling erase() function : " << str;
}





Output




The string is : Welcome
The modified string after calling erase() function : Welme








• replace() function


This function replaces part of a string with another string.



// The replace() function in string class.

#include<iostream>
#include<string>

using namespace std;

int main()
{
string str("Ting tong");
cout<<"The string is : " << str <<"\n";

string str2("XYZ");

//Calling replace() function to replace part of a string with another string.
str.replace(0,2,str2);
cout<<"The modified string after calling append() function : " << str;
}





Output




The string is : Ting tong
The modified string after calling replace() function : XYZng tong






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• length() function


This method gives us the total length of a string i.e. total number of characters that make a string.



// The length() function in string class.

#include<iostream>
#include<string>

using namespace std;

int main()
{
string str1;

//Calling length() function to check length of an empty string.
cout<< "The length of first string is : " << str1.length() << "\n";

string str2("Welcome");
cout<<"The length of second string is : " << str2.length();
}





Output




The length of first string is : 0
The length of second string is : 7








• at() function


This method gives us a character present at a particular index in a string.



// The at() function in string class.

#include<iostream>
#include<string>

using namespace std;

int main()
{
string str1("Welcome");
cout<< "The string value is : " << str1 << "\n";
cout<< "The character at the index 2 in string : " << str1.at(2);
}





Output




The string value is : Welcome
The character at the index 2 in string : l








• swap() function


This method swaps one string with the content of another string.



// The swap() function in string class.

#include<iostream>
#include<string>

using namespace std;

int main()
{
string str1("Welcome");
cout<< "The string value in the first string : " << str1 << "\n";


string str2("Hello");
cout<< "The string value in the second string : " << str2 << "\n";

//Calling swap() function to swap the values of two strings
str1.swap(str2);

cout<< "The string value in the first string after swap() : " << str1 << "\n";
cout<< "The string value in the second string after swap() : " << str2 << "\n";

return 0;
}





Output




The string value in the first string : Welcome
The string value in the second string : Hello
The string value in the first string after swap() : Hello
The string value in the second string after swap() : Welcome








• find() function


This method finds part of a string i.e. substring.



// The find() function in string class.

#include<iostream>
#include<string>

using namespace std;

int main()
{
string str1("Welcome");
cout<< "The string is : " << str1 << "\n";

string substr = "come";
cout<< "The substring to find in a string : " <lt; substr;
//Finding the substring "come" in the string
int index = str1.find(str);

cout<< "The index of the found substring in the string is : " << index;
}





Output




The string is : Welcome
The substring to find in a string : come
The index of the found substring in string is : 3








• substr() function


This method finds and returns part of a string i.e. substring.



// The substr() function in string class.

#include<iostream>
#include<string>

using namespace std;

int main()
{
string str1("Welcome");
cout<< "The string is : " << str1 << "\n";

//Finding the substring starting at index 0 and ending at index 2 in the string
string subs= str1.substr(0,2);

cout<< "The found substring in the string is : " << subs;
}





Output




The string is : Welcome
The found substring in the string is : We








• find_first_of() function


This method returns us the index of the first occurrence of a String in a String



// The find_first_of() function in string class.

#include<iostream>
#include<string>

using namespace std;

int main()
{
string str1("Welcome");
cout<< "The string is : " << str1 << "\n";

//Finding the index of the first occurrence of a  character in the string
int index= str1.find_first_of('e');

cout<< "The index of the first occurrence of the character e in string is : " << index;
}





Output




The string is : Welcome
The index of the first occurrence of the character e in string is : 1








• find_first_of() function




// The swap() function in string class.

#include<iostream>
#include<string>

using namespace std;

int main()
{
string str1("Welcome");
cout<< "The string is : " << str1 << "\n";

//Finding the index of the first occurrence of a  character in the string
int index= str1.find_first_of('e');

cout<< "The index of the first occurrence of the character e in string is : " << index;
}





Output




The string is : Welcome
The index of the first occurrence of the character e in string is : 1








• find_last_of() function


This method returns us the index of the last occurrence of a particular character in a String.



// The find_last_of() function in string class.

#include<iostream>
#include<string>

int main()
{
string str1("Welcome");
cout<< "The string is : " << str1 << "\n";

//Finding the index of the last occurrence of a  character in the string
int index= str1.find_last_of('e');

cout<< "The index of the last occurrence of the character e in string is : " << index;
}





Output




The string is : Welcome
The index of the last occurrence of the character e in string is : 6








• capacity() function


This method returns the total number of elements that can be stored in a string.



// The capacity() function in string class.

#include<iostream>
#include<string>

int main()
{
string str1;

//Calling capacity() function to check length of an empty string.
cout<< "The capacity of first string is : " << str1.capacity() << "\n";

string str2("Welcome");
cout<<"The capacity of second string is : " << str2.capacity();
}





Output




The capacity of first string is : 15
The capacity of second string is : 15








• capacity() function




// The capacity() function in string class.

#include<iostream>
#include<string>

int main()
{
string str1;

//Calling capacity() function to check capacity of an empty string.
cout<< "The capacity of first string is : " << str1.capacity() << "\n";

string str2("Welcome");

//Calling capacity() function to check capacity of an non-empty string.
cout<<"The capacity of second string is : " << str2.capacity();
}





Output




The capacity of first string is : 15
The capacity of second string is : 15








• empty() function


This method returns true if the string is empty or false, if it is not. The empty() function returns 1 if string is empty and 0 if it is not empty.



// The empty() function in string class.

#include<iostream>
#include<string>

int main()
{
string str1;

//Calling empty() function to check if the string is empty or not
cout<< "The length of first string is : " << str1.empty() << "\n";

string str2("Welcome");

//Calling empty() function to check if the string is empty or not
cout<<"The length of second string is : " << str2.empty();
}





Output




The length of first string is : 1
The length of second string is : 0








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