Python help() Function

Python3 内置函数Python3 Built-in Functions

help()It is a built-in function in Python used to get help information about built-in functions, modules, objects, etc.

When you have questions about how to use a function or module,help()it is the best query tool. It will display detailed docstrings to help you understand the function's functionality, parameters, and return values.

Word Definition： helpMeans "help", used to obtain documentation information.

Basic Syntax and Parameters

Syntax Format

help(object)
help('topic')

Parameter Description

  • Parameter object：
    • Type: Any object (function, class, module, etc.)
    • Description: The object for which to obtain help information.
  • Parameter topic：
    • Type: string
    • Description: Topic name, such as module name, function name, keyword, etc.

Function Description

  • Return value: No return value; directly prints help information in the interactive environment.
  • Usage Scenarios：
    • Query function usage
    • Query module functions
    • Learn Python syntax

Examples

Example 1: View function help

Examples

# View help for the len function
help(len)
# Output:
# Help on built-in function len in module builtins:
# len(obj, /)
#     Return the number of items in a container.

# View help for the print function
help(print)
# Output:
# Help on built-in function print in module builtins:
# print(...)
#     print(value, ..., sep=' ', end='\n', file=sys.stdout, flush=False)
#     Prints the values to a stream or to sys.stdout by default.

# View help for an object
help([].append)
# Output:
# Help on method_descriptor:
# append(self, object, /) method of builtins.list instance
#     L.append(object) -> None -- append object to end

Code Analysis:

  1. Directly pass the function name (without parentheses) to view help.
  2. The help information includes function signature, parameter descriptions, and functional description.
  3. For methods, you can also get help through the object.

Example 2: View help for modules and topics

Examples

# View help for a module
import os
help(os)
# Will display the detailed documentation of the os module, including descriptions of all functions and constants

# View a specific topic
help("modules")
# Will list all available modules

help("keywords")
# Will list all Python keywords

help("assert")
# Will show the usage of the assert statement

Code Analysis:

  • You can view the documentation of an entire module.
  • Using a string parameter lets you view help for a specific topic.
  • The "modules" topic lists all installed modules.

Example 3: Using help in a script

Examples

# Interactive use (most common)
# >>> help(list)
# Will display all methods of the list class

# View help for data types
help(int)     # Integer type
help(str)    # String type
help(dict)   # Dictionary type
help(tuple)  # Tuple type

# View help for exceptions
help(ZeroDivisionError)
help(ValueError)

# View syntax help
help("with")
help("for")
help("if")

Expected Output:

Running the above code in an actual interactive Python environment will display detailed help documentation.

help()It is one of the most powerful tools for learning Python, and it is recommended to use it frequently in daily programming.

Python3 内置函数Python3 Built-in Functions

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