File Output and Input article

wiki/cpp-tutorial/file-io.md

@@ -1,3 +1,66 @@
 ---
 wip: true
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+
+# File Input and Output
+In C++, you can use the `fstream` library to create, write and read files. \
+To use fstream, you need to include the `<iostream>` **AND** `<fstream>` header files.
+
+``` cpp
+#include <iostream>
+#include <fstream> 
+```
+The `<fstream>` library provides three main classes:
+|Function|Description|
+|--------|-----------|
+|`std::ofstream`|Used to create and write to files|
+|`std::ifstream`|Used to read from files|
+|`std::fstream`|Used for both reading and writing|
+
+::: info Note
+`std::fstream` is a general-purpose file stream, while `std::ifstream` and `std::ofstream` are more specific and commonly used in practice.
+:::
+
+## Read a File (`std::ifstream`) {#read-a-file}
+`std::ifstream` is used to read data from a file.
+
+``` cpp
+std::string line;
+
+std::ifstream file("filename.txt");
+
+if (!file) return 1;
+
+while (std::getline(file, line)) {
+    std::cout << line << "\n";
+}
+
+file.close();
+```
+
+Using a `while` loop with `getline()` allows us to read a file line by line until we reach the end, and then print each line.
+
+## Write a File (`std::ofstream`) {#write-a-file}
+`std::ofstream` is used to write data to a file.
+
+``` cpp
+std::ofstream file("filename.txt");
+
+if (!file) return 1;
+
+file << "Hello Together C & C++!";
+
+file.close();
+```
+This will create the file if it doesn’t exist, or overwrite it if it already exists.
+
+## Redirecting standard input/output {#redirecting-stdio}
+`freopen` is used to redirect standard input and output streams to files.\
+It reassigns `stdin` or `stdout` to a file instead of the default console input/output.
+``` cpp
+freopen("input.txt", "r", stdin);
+freopen("output.txt", "w", stdout);
+```
+::: info Note
+`freopen` is commonly used in competitive programming for convenience, but it is not recommended for general C++ applications.
+:::

wiki/cpp-tutorial/sidebar.ts

@@ -134,7 +134,25 @@ const sidebar = [
                 ],
                 collapsed: true,
             },
-            { text: "File Input and Output", link: "/cpp-tutorial/file-io" },
+            { 
+                text: "File Input and Output", 
+                link: "/cpp-tutorial/file-io",
+                items: [
+                    {
+                        text: "Read a File",
+                        link: "/cpp-tutorial/file-io#read-a-file",
+                    },
+                    {
+                        text: "Write a File",
+                        link: "/cpp-tutorial/file-io#write-a-file",
+                    },
+                    {
+                        text: "Redirecting standard input/output",
+                        link: "/cpp-tutorial/file-io#redirecting-stdio",
+                    },
+                ],
+                collapsed: true,
+            },
             {
                 text: "User Defined Types",
                 link: "/cpp-tutorial/user-defined-types",