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std::string::rfind in C++ with Examples

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  • Difficulty Level : Easy
  • Last Updated : 26 May, 2022
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The std::string::rfind is a string class member function that is used to search the last occurrence of any character in the string. If the character is present in the string then it returns the index of the last occurrence of that character in the string else it will return string::npos which denotes the pointer is at the end of the string. Header File:

#include < string >

Syntax 1:

rfind(char ch)
rfind(string str)

Parameters: This function takes a given character or a string as a parameter, whose index is to be found. Return value: This method returns the position of the last occurrence of that character or first index of the last occurrence of the string. Program 1: Below is the program to illustrate string::rfind(char ch)

CPP




// C++ program to demonstrate
// rfind() method
 
#include <cstddef>
#include <iostream>
#include <string>
using namespace std;
 
// Function to return last occurrence
// of character in a string
void findLastOccurrence(string str, char ch)
{
 
    // To store the index of the result
    size_t found;
 
    // Function to find the last
    // occurrence of character ch
    // in string str
    found = str.rfind(ch);
 
    // If string doesn't have
    // character ch present in it
    if (found == string::npos) {
        cout << "Character " << ch
             << " is not present in"
             << " the given string.";
    }
 
    // Else print the position
    else {
        cout << "The last occurrence of '"
             << ch << "' is found at index: "
             << found << endl;
    }
}
 
// Driver Code
int main()
{
    // Given String
    string str("Welcome to GeeksforGeeks!");
 
    // Character to be found
    char ch = 'e';
 
    findLastOccurrence(str, ch);
}


Output:The last occurrence of ‘e’ is found at index: 21

Program 2: Below is the program to illustrate string::rfind(string str)

CPP




// C++ program to demonstrate
// rfind() method
 
#include <cstddef>
#include <iostream>
#include <string>
using namespace std;
 
// Function to return last occurrence
// of string in a string
void findLastOccurrence(string str, string s)
{
 
    // To store the index of the result
    size_t found;
 
    // Function to find the first index
    // of last occurrence of string s in str
    found = str.rfind(s);
 
    // If string doesn't have
    // string s present in it
    if (found == string::npos) {
        cout << "String '" << s
             << "' is not present in"
             << " the given string.";
    }
 
    // Else print the position
    else {
        cout << "The first index of last "
             << "occurrence of '" << s
             << "' is found at index: "
             << found << endl;
    }
}
 
// Driver Code
int main()
{
    // Given String
    string str("Welcome to GeeksforGeeks!");
 
    // string to be found
    string s = "to";
 
    findLastOccurrence(str, s);
}


Output:The first index of last occurrence of ‘to’ is found at index: 8

Syntax 2:

rfind(char ch, size_t position);
rfind(string s, size_t position); 

Parameters: This function takes:

  • a given character or a string as a parameter, whose index is to be found.
  • a position till where the search is to be performed.

Return value: This method returns the position of the first character of the last match of that given character or string before that position else it returns string::npos Program 3: Below is the program to illustrate string::rfind(char ch, size_t position): 

CPP




// C++ program to illustrate the function
// string::rfind(char ch, size_t pos)
 
#include <cstddef>
#include <iostream>
#include <string>
using namespace std;
 
// Function to return last occurrence
// of character in a string
void findLastOccurrence(
    string str, char ch, size_t position)
{
 
    // To store the index of the result
    size_t found;
 
    // Function to find the last occurrence
    // of character ch in str before pos 5
    found = str.rfind(ch, position);
 
    // If string doesn't have
    // character ch present in it
    if (found == string::npos) {
        cout << "Character " << ch
             << " is not present in"
             << " the given string.";
    }
 
    // Else print the position
    else {
        cout << "The last occurrence of "
             << ch << " before position "
             << position
             << " is found at index: "
             << found << endl;
    }
}
 
// Driver Code
int main()
{
    // Given String
    string str("Welcome to GeeksforGeeks!");
 
    // Character to be found
    char ch = 'e';
 
    // Position till where
    // the search is to be done
    size_t position = 5;
 
    findLastOccurrence(str, ch, position);
}


Output:The last occurrence of e before position 5 is found at index: 1

Program 4: Below is the program to illustrate string::rfind(string str, size_t position): 

CPP




// C++ program to illustrate the function
// string::rfind(string str, size_t pos)
#include <cstddef>
#include <iostream>
#include <string>
using namespace std;
 
// Function to return last occurrence
// of string in a string
void findLastOccurrence(
    string str, string s, size_t position)
{
 
    // To store the index of result
    size_t found;
 
    // Function to find the last occurrence of
    // string s in str before given position
    found = str.rfind(s, position);
 
    // If string doesn't have
    // string s present in it
 
    // If string doesn't have
    // string s present in it
    if (found == string::npos) {
        cout << "String " << s
             << " is not present in"
             << " the given string.";
    }
 
    // Else print the position
    else {
        cout << "The last occurrence of "
             << s << " before position "
             << position
             << " is found at index: "
             << found << endl;
    }
}
 
// Driver Code
int main()
{
 
    // Given String
    string str("Welcome to GeeksforGeeks!");
 
    // string to be found
    string s = "to";
 
    // Position till where
    // the search is to be done
    size_t position = 5;
 
    findLastOccurrence(str, s, position);
}


Output:String to is not present in the given string.

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