[Entry] C++ Strings: rfind()

content/cpp/concepts/strings/terms/rfind/rfind.md

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+---
+Title: 'rfind()'
+Description: 'Searches a string from right to left and returns the last occurrence of a substring or character.'
+Subjects:
+  - 'Computer Science'
+  - 'Game Development'
+Tags:
+  - 'Containers'
+  - 'Methods'
+  - 'STL'
+  - 'Strings'
+CatalogContent:
+  - 'learn-c-plus-plus'
+  - 'paths/computer-science'
+---
+
+The C++ **`rfind()`** [function](https://www.codecademy.com/resources/docs/cpp/functions) returns the position of the last occurrence of a given substring or character within a `std::string`. The search proceeds from right to left, and the function returns `std::string::npos` if no match is found.
+
+## Syntax
+
+```pseudo
+string_object.rfind(val, pos = npos);
+```
+
+**Parameters:**
+
+- `val`: A character or string to search for.
+- `pos` (Optional): The position to start searching backward from. Defaults to `std::string::npos`, meaning the end of the string.
+
+**Return value:**
+
+Returns the index (zero-based) of the last occurrence of val, or `std::string::npos` if no match is found.
+
+## Example 1
+
+In this example, `rfind()` locates the last occurrence of a substring:
+
+```cpp
+#include <iostream>
+#include <string>
+
+int main() {
+  std::string text = "hello world, welcome to the world";
+
+  std::size_t pos = text.rfind("world");
+  std::cout << "Last occurrence of 'world': " << pos << "\n";
+
+  return 0;
+}
+```
+
+The output of this code is:
+
+```shell
+Last occurrence of 'world': 28
+```
+
+## Example 2
+
+In this example, `rfind()` is used to locate the last occurrence of a character:
+
+```cpp
+#include <iostream>
+#include <string>
+
+int main() {
+  std::string text = "abracadabra";
+
+  std::size_t pos = text.rfind('a');
+  std::cout << "Last 'a' found at index: " << pos << "\n";
+
+  return 0;
+}
+```
+
+The output of this code is:
+
+```shell
+Last 'a' found at index: 10
+```
+
+## Codebyte Example
+
+In this example, the position of the last occurrence of a character is printed using `rfind()`:
+
+```codebyte/cpp
+#include <iostream>
+#include <string>
+
+int main() {
+  std::string word = "mississippi";
+
+  std::size_t pos = word.rfind('s');
+  std::cout << "Last 's' found at index: " << pos << "\n";
+
+  return 0;
+}
+```
+
+## Frequently Asked Questions
+
+### 1. What does `rfind` do in C++?
+
+The `rfind()` function searches a string from right to left and returns the index of the last occurrence of a character or substring. If the value is not found, it returns `std::string::npos`. It is useful when the needed match appears multiple times and the last one is required.
+
+### 2. What does `string::find()` do in C++?
+
+The `find()` function searches a string from left to right and returns the index of the first occurrence of a specified character or substring. Like `rfind()`, it returns `std::string::npos` when no match exists.
+
+### 3. What does `string()` do in C++?
+
+Calling `std::string()` constructs an empty string object. It represents a dynamic sequence of characters and supports operations such as insertion, erasure, concatenation, comparison, and searching.