How to define function return value in python

Introduction to return value:

A brief introduction to the difference between print and return. Print only prints on the console, while return uses the part after return as the return value. As the output of the function, you can use a variable to take it away and continue to use the return value to do other things.

The function needs to be defined first and then called. The result of the return statement in the function body is the return value. If a function does not have a return statement, it actually has an implicit return statement, the return value is None, and the type is 'NoneType'.

The function of the return statement: end the function call and return the value

Specified return value and implicit return value

What is returned when the return statement in the function body has a specified return value Its value

When there is no return statement in the function body, the function will implicitly return None as the return value after running. The type is NoneType, which is equivalent to return and returnNone, both of which return None.

Specify return return value function example:

def showplus(x): print(x) return x + 1 num = showplus(6) add = num + 2 print(add) 输出结果： 6 9

Implicit returnNone example:

def showplus(x): print(x) num = showplus(6) print(num) print(type(num)) 输出结果： 6 None 

Return statement position and multiple return statements

Python function uses return The statement returns a "return value", which can be assigned to other variables for other purposes;

All functions have return values. If there is no return statement, returnNone will be implicitly called as the return value;

A function can have multiple return statements, but only one can be executed. If no return statement is executed, returnNone will also be implicitly called as a return;

If necessary, it can be called explicitly returnNone clearly returns a None (null value object) as the return value, which can be abbreviated as return. However, laziness is a virtue in python, so it is generally not written if you can;

If the function executes the return statement, the function will Return immediately, end the call, and other statements after return will not be executed

def showplus(x): print(x) return x + 1 print(x + 1) #该语句会执行么 print(showplus(6)) 输出结果： 6 7

Return value type

No matter what type is defined to be returned, return can only return a single value, but the value There can be multiple elements;

return [1,3,5] refers to returning a list, which is a list object, 1,3,5 are the elements of this list respectively;

return 1,3,5 seems to return multiple values, and is implicitly encapsulated by Python into a primitive return

Example 1:

def showlist(): return [1,3,5] #多元素，返回的是什么类型 print(type(showlist())) print(showlist()) 输出结果：  [1, 3, 5] #列表类型

Example 2:

def showlist(): return 2,4,6 #多值时，不指定类型 print(type(showlist())) print(showlist()) 输出结果：  #默认封装成元祖类型

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