Return and execution of return in python

The return statement in Python is used to return the value of a function. It has two main functions: one is to return the result to the caller, and the other is to terminate the function early. execution.

In Python, a function can return one or more values ​​through the return statement. When a return statement is encountered, the function will immediately stop execution and return the value of the expression following return to the caller. If no return statement is explicitly specified, the function will return None by default.

The following uses specific code examples to illustrate the use of return:

def add(x, y):
    return x + y

sum = add(2, 3)  # 调用add函数，并将返回值赋给sum变量
print(sum)  # 输出结果为5

In the above code, the add function receives two parameters x and y, and returns their sum to the caller through the return statement . Call the add function in the main program, assign the return value to the sum variable, and then print the sum value.

In addition to returning a single value, return can also return multiple values. In Python, multiple values ​​can be represented as tuples, lists, or other iterable objects.

def divide(x, y):
    if y != 0:
        return x / y, x % y
    else:
        return "Error: divisor cannot be zero"

result, remainder = divide(10, 3)  # 调用divide函数，并将返回的两个值分别赋给result和remainder变量
print("Result:", result)  # 输出结果为3.3333333333333335
print("Remainder:", remainder)  # 输出结果为1

error = divide(10, 0)
print(error)  # 输出结果为 "Error: divisor cannot be zero"

In the above code, the divide function determines whether the divisor is 0. If it is not 0, return the quotient and remainder; if it is 0, return an error message. Call the divide function in the main program, assign the returned multiple values ​​to the result and remaining variables, and then print them out respectively. When the divide function is called for the second time, a string is returned representing the error message.

In addition, the return statement can also terminate the execution of the function early. In a function, when a return statement is encountered, the function will immediately stop execution and return the value of the expression following return to the caller.

def is_even(num):
    if num % 2 == 0:
        return True
    else:
        return False
        print("This code will not be executed")

result = is_even(4)
print(result)  # 输出结果为True

In the above code, the is_even function receives an integer parameter num to determine whether it is an even number. If it is an even number, return True; otherwise, return False. There is a print statement immediately following the if statement, but this statement is never executed because execution of the function has terminated after the return statement.

Through the above code examples, we can clearly understand the return and execution mechanism of the return statement in Python. Return is not only used to return results to the caller, but also to terminate the execution of the function early, making the function more flexible and efficient. When writing functions, rational use of return statements can improve the readability and maintainability of the code.

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