len If a class behaves like a list, to get the number of elements, you have to use the len() function. For the len() function to work properly, the class must provide a special method len(), which returns the number of elements. For example, we write a Students class and pass the name in: class Students(object): def init(self, *args): self.names = args def len(self): return&
1. In-depth understanding of the special function __len__(self) in python
# Introduction: len If a class behaves like a list, to get how many elements there are, you have to use the len() function. For the len() function to work properly, the class must provide a special method len(), which returns the number of elements. For example, we write a Students class and pass the name in:
2. Summary of common special operation symbols and functions in php
Introduction: Annotation symbols: // Single-line annotation Use of quotation marks for multi-line annotation ' ' Single quotation mark, simple string, taken directly without any processing; " "Double quotes, PHP dynamic processing and then output, generally used to process $ variables.
#Introduction: Python has some built-in special functions, which are very python-specific. Can make the code more concise. You can see the example: 1 filter(function, sequence): str = [& 39;a&
4. Collection of special functions in Python
Introduction: This article mainly introduces the special functions in Python, mainly introducing four functions: 1 Filtering Function filter 2 mapping and merging function map/reduce 3 decorator @ 4 anonymous function lamda, friends who need it can refer to
Introduction: Functions are declared in this way: keyword function, function name, a set of parameters, and The code to be executed in parentheses; the Function() constructor is actually a fully functional object
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