70、递归机制详解与应用实践

递归机制详解与应用实践

1. 递归的工作原理

递归是一种强大的编程技术，在 Python 中，函数调用的管理通过栈来实现。Python 会将每次函数调用的命名空间压入栈中，以此跟踪函数调用。下面以阶乘函数为例，深入探讨递归的工作机制。

def factorial(n):
    """Recursive Factorial with print to show operation . """
    indent = 4*(6-n)*" "
    # more indent on deeper recursion
    print(indent + "Enter factorial n = ", n)
    if n == 1:
        # base case
        print(indent + "Base case.")
        return 1
    else:
        # recursive case
        print(indent + "Before recursive call f(" + str(n-1) + ")")
        # separate recursive call allows print after call
        rest = factorial(n-1)
        print(indent + "After recursive call f(" + str(n-1) + ") = ", rest)
        return n * rest

当调用 factorial(4)