# File Handling

File handling is a fundamental aspect of programming, allowing us to read and write data to and from files.

## Opening and Closing Files

Before performing any file operation, we need to open the file. Python provides the `open()` function for this purpose. The `open()` function takes two arguments: the filename and the mode in which the file should be opened. The mode can be specified as `"r"` for reading, `"w"` for writing, or `"a"` for appending to an existing file.

```python
file_read = open("example.txt", "r")  # Read mode
file_write = open("example.txt", "w")  # Write mode
file_append = open("example.txt", "a")  # Append mode
file_binary = open("example.bin", "rb")  # Binary read mode
file_text = open("example.txt", "rt")  # Text read mode
file_update = open("example.txt", "r+")  # Read and update mode
file.close()  # Close the file
```

Using `with` keyword. When we use this keyword we do not need to explicitly close our .file

```python
with open("example.txt", "r") as file:
    content = file.read()
    print(content)
```

## Reading from Files

Python offers different methods for reading data from files.

### 1\. Reading the Entire File

To read the entire contents of a file, we can use the `read()` method. It reads the entire file content as a string.

```python
'''First create example.txt'''
file = open("example.txt", "r")
content = file.read()
print(content)
file.close()
```

### 2\. Reading Line by Line

To read a file line by line, we can use a `for` loop. Each line can be accessed as a string.

```python
file = open("example.txt", "r")
for line in file:
    print(line)
file.close()
```

### 3\. Reading a Specific Number of Characters

If we want to read a specific number of characters from a file, we can use the `read(n)` method, where `n` represents the number of characters to be read.

```python
file = open("example.txt", "r")
content = file.read(10)  # Read first 10 characters
print(content)
file.close()
```

## Writing to Files

Python provides several methods for writing data to files. Let's explore some of the common approaches:

### 1\. Writing to an Empty File

To write data to a file, open the file in write mode (`"w"`) or append mode (`"a"`) and use the `write()` method.

```python
file = open("example.txt", "w")
file.write("Hello, World!")
file.close()

'''
Output open example.txt:
-------------------------
Hello, World!
'''
```

This code creates a new file called **"example.txt"** and writes the text **"Hello, World!"** `to` it. If the file already exists, it will be overwritten.

### 2\. Appending to an Existing File

If we want to add content to an existing file without overwriting the existing data, we can open the file in append mode (`"a"`) and use the `write()` method.

```python
file = open("example.txt", "a")
file.write("This is an appended line.")
file.close()
'''
Output : open example.txt
-------------------------
Hello, World!
This is an appended line.
'''
```