What are python built-in functions?

Python's built-in functions are functions that can be used directly without importing modules. They are divided into three categories: type conversion, mathematical operations, and object operations. ① Type conversion functions include int() to convert strings or floating-point numbers into integers, str() to strings, list() and tuple() to iterable objects, float() to floating-point types, but illegal conversions will cause errors to be reported and exceptions need to be handled; ② Mathematical and comparison functions include abs() to take absolute values, round() rounding, min()/max() to find the minimum maximum value, sum() to sum elements, which is suitable for data analysis and algorithm writing; ③ Object and structure operation functions such as len() to obtain length, type() and isinstance() to judge types, id() to view memory addresses, dir() to list attribute methods, input() to receive input, and print() to output content, suitable for debugging and interactive programming. Familiar with these commonly used functions can significantly improve code efficiency.

Python's built-in functions are those that can be used directly without additional import modules. They are part of the Python language and cover multiple aspects, from data type conversion, mathematical operations to object operations.

Common type conversion functions

These functions are very useful when dealing with different types of data, such as converting strings into integers, or turning lists into tuples.

• int() : converts a string or floating point number into an integer, for example int("123") returns 123
• str() : convert other types into strings, such as str(456) to get "456"
• list() and tuple() : It can convert iterable objects (such as strings, collections) into lists or tuples
• float() : converts a numeric string or integer into a floating point type

It should be noted that if the converted content is illegal, such as using int("abc") , the program will report an error, so it is best to cooperate with exception handling in actual use.

Commonly used math and comparison functions

Although many math functions are placed in the math module, there are also some practical gadgets built-in:

• abs() : Returns the absolute value of a number, such as abs(-5) to get 5
• round() : round(3.6) is 4 and round(3.4) is 3
• min() and max() : Find the minimum or maximum value in a set of data, supports multiple parameters and even iterable objects
• sum() : Sum of elements in an iterable object, often used for a set of numbers in a list or tuple

These functions often appear in data analysis and algorithm writing, and are simple but very practical.

Operation functions on objects and structures

Some built-in functions can help us view object properties, judge types, or perform logical control.

• len() : Get the object length, suitable for strings, lists, dictionaries, etc.
• type() and isinstance() : used to judge variable types, the latter is more suitable for inheritance relationship judgment
• id() : View the unique identifier of the object (memory address)
• dir() : Lists all available properties and methods of the object, which is useful during debugging.
• input() : Receive user input, suitable for interactive scripts
• print() : output content, the first function to be exposed to by almost every beginner

For example, if you write a mini program and want the user to enter a name, you can do this:

 name = input("Please enter your name:")
print("Hello,", name)

Basically that's it. Python has many built-in functions, but only dozens of commonly used ones can be used. After getting familiar with them, you can greatly improve code efficiency. Some details may be easily overlooked, such as how to deal with round() in .5, or the difference between isinstance() and type() , but you will know these problems by looking at the documentation or trying them.

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