# Error Handling

Error handling is the process of anticipating, detecting, and resolving programming, application, and communications errors. It prevents the program from crashing and allows for graceful recovery or logging.

## 1. The Try-Catch Block

The core mechanism for handling runtime errors is the `try-catch` block.

*   **Try:** Contains the code that might throw an exception.
*   **Catch:** Contains the code that executes if an exception occurs.

### JavaScript / Java / C++
```javascript
try {
    // Code that might fail
    let result = riskyOperation();
} catch (error) {
    // Code to handle the error
    console.error("Something went wrong:", error);
}
```

### Python
Python uses `try` and `except`.
```python
try:
    result = 10 / 0
except ZeroDivisionError:
    print("Cannot divide by zero")
except Exception as e:
    print(f"An error occurred: {e}")
```

## 2. The Finally Block

The `finally` block contains code that will **always** execute, regardless of whether an error occurred or not. It is typically used for cleanup (closing files, database connections).

```javascript
try {
    openFile();
    readFile();
} catch (e) {
    handleError(e);
} finally {
    closeFile(); // Always runs
}
```

## 3. Throwing Exceptions

You can manually trigger an error using the `throw` (or `raise` in Python) keyword.

*   **JavaScript:** `throw new Error("Something bad happened");`
*   **Python:** `raise ValueError("Invalid value")`
*   **Java:** `throw new IllegalArgumentException("Invalid argument");`

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[[programming/common-syntax]]