PyCharm Python Debugging Tips: Deep Understanding of Debugging Mechanism for Fast Problem Identification

# 1. Introduction to PyCharm Python Debugging

Python debugging is the process of discovering and resolving errors and issues in Python code. PyCharm is a popular Python Integrated Development Environment (IDE) that offers robust debugging capabilities to help developers quickly and accurately identify and fix problems.

The PyCharm debugger interface is user-friendly, allowing developers to set breakpoints, inspect variables, evaluate expressions, and step through code. By utilizing these features, developers can gain an in-depth understanding of the code execution flow and isolate the specific lines or functions causing the issue.

# 2. Basics of PyCharm Python Debugging

### 2.1 Debugger Interface and Operations

The PyCharm debugger interface offers an intuitive interactive environment to control and inspect code execution.

- **Debugging Toolbar:** Contains controls for starting, stopping, stepping, and setting breakpoints.
- **Variables View:** Displays available variables in the current scope and their values.
- **Stack View:** Shows the current function call stack.
- **Breakpoints View:** Lists set breakpoints.
- **Console:** Used for entering commands and viewing debugging output.

**Debugging Operations:**

- **Start Debugging:** Press F5 or click the green triangle icon on the debugging toolbar.
- **Stop Debugging:** Press Shift+F5 or click the red square icon on the debugging toolbar.
- **Step Debugging:**
- **F7 (Step Into):** Enter a function call.
- **F8 (Step Over):** Skip a function call.
- **F9 (Continue):** Execute code until the next breakpoint or function return.
- **Set Breakpoints:** Click on the code line or press F9, or right-click in the breakpoints view and select "Add Breakpoint."
- **Conditional Breakpoints:** Set conditions for breakpoints in the breakpoints view, triggering only when the condition is true.

### 2.2 Setting Breakpoints and Conditional Breakpoints

Breakpoints are powerful tools in the debugger used to pause execution at specific code lines. PyCharm offers flexible options for breakpoint settings, including conditional breakpoints.

**Types of Breakpoints:**

- **Line Breakpoints:** Pause execution at a specific code line.
- **Exception Breakpoints:** Pause execution when a specific exception is raised.
- **Conditional Breakpoints:** Pause execution only when a specific condition is met.

**Setting Conditional Breakpoints:**

1. Right-click on an existing breakpoint in the breakpoints view or click the "Add Breakpoint" button.
2. Enter a Boolean expression in the "Condition" field.
3. The breakpoint will trigger only when the condition is true.

**Example:**

def my_function(a, b):
     if a > b:
         return a
     else:
         return b

# Set a conditional breakpoint to trigger only when a is greater than b
breakpoint(condition=a > b)

### 2.3 Debugging Variables and Expressions

Debugging variables and expressions is crucial for examining the state of code execution. PyCharm provides multiple ways to evaluate and modify variables.

**Variables View:**

- In the variables view, you can view the available variables in the current scope.
- Double-click a variable to see its value and type.
- Use the "Modify Value" button to change variable values.

**Expression Evaluation:**

- In the console, input an expression and press Enter to evaluate it.
- Expressions can include variables, function calls, and operators.
- The evaluation result will be displayed in the console.

**Example:**

# Evaluate an expression in the console
>>> print(my_variable)
10

**Code Block:**

# Evaluate an expression in a code block
import pdb; pdb.set_trace()
print("Hello world")

**Logical Analysis:**

- Set breakpoints and run the code.
- At breakpoints, use the variables view to inspect variable values.
- Evaluate expressions in the console to check code logic.
- Use step debugging to trace code execution and identify issues.

# 3.1 Stack Traces and Exception Handling

Stack traces are an essential tool in the debugging process, providing a snapshot of the function call stack during program execution. When an exception occurs, the stack trace displays where the exception occurred and the function call chain that led to the exception.

#### Stack Trace Analysis

Stack traces typically start with the lowest-level function calls, then proceed upwards until the location of the exce