How to extract useful information from error stack?

The error stack is a record generated when an error is encountered during program execution, including the error type, location and possible causes. When extracting useful information, first determine the error type (such as TypeError); second, find the error location, represented by "File" and line number; and finally, view the error message to get more details, such as undefined variables. Through practical cases, we can learn how to extract useful information from the error stack, including error type, error location, and error information.

Extract useful information from the error stack

The error stack is a text record generated when an error is encountered during program execution. It contains key information about the error type, location, and possible causes. Learning how to extract useful information from the error stack is important for debugging and fixing your code.

Understand the error stack structure

The error stack is usually represented in the following format:

Exception: TypeError
Traceback (most recent call last):
  File "my_script.py", line 10, in <module>
    print(x.split())
NameError: name 'x' is not defined

Extract useful information

1. Error type: The first line of the error stack identifies the error type, such as TypeError in the previous example.
2. Error location: Next is a set of lines starting with "File" and a line number indicating where the error occurred. The bottom line indicates the line of code where the error occurred. In the example, this means that the error was thrown at line 10 of "my_script.py".
3. Error message: The last line provides more details for the error message, such as "name 'x' is not defined", indicating that an undefined variable "x" is referenced.

Practical case

Consider the following Python script:

def calculate_average(nums):
  sum = 0
  for num in nums:  # nums 应该是一个数组
    sum += num
  return sum / len(nums)

# 空数组
average = calculate_average([])

Running this script will generate the following error stack:

---------------------------------------------------------------------------
ZeroDivisionError                            Traceback (most recent call last)
/Users/user/Documents/calculate_average.py in calculate_average(nums)
      9 return sum / len(nums)
ZeroDivisionError: division by zero

From this we can extract the following useful information:

• Error type: ZeroDivisionError
• Error location: Line 9 of the script
• Error message: The divisor is 0

This message indicates that an empty array was passed to the "calculate_average" function when calculating the average, resulting in a divisor of Zero errors.

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