Question

def azalt(s):
    if len(s)< 1:
        return s
    else:
        print( özyinelemesürecine girerken: , s)
        azalt(s[1:])
        print( özyinelemesürecinden çıkarken: , s)

azalt( 12345 )

产出:

özyinelemesürecine girerken: 12345
özyinelemesürecine girerken: 2345
özyinelemesürecine girerken: 345
özyinelemesürecine girerken: 45
özyinelemesürecine girerken: 5 #(***)
özyinelemesürecinden çıkarken: 5 
özyinelemesürecinden çıkarken: 45
özyinelemesürecinden çıkarken: 345
özyinelemesürecinden çıkarken: 2345
özyinelemesürecinden çıkarken: 12345

i. 在<代码>#(***)(i.

i 预期产出就这样看。

产出:

özyinelemesürecine girerken: 12345
özyinelemesürecine girerken: 2345
özyinelemesürecine girerken: 345
özyinelemesürecine girerken: 45
özyinelemesürecine girerken: 5

Answer 1

For better understanding you can add another parameter to the function (lets call it level=) that will increase by 1 when you call the function recursively:

def azalt(s, level):
    if len(s) < 1:
        return s
    else:
        print("the string before:", s, f"{level=}")
        azalt(s[1:], level + 1)
        print("the string after:", s, f"{level=}")


azalt("12345", level=1)

结果是:

the string before: 12345 level=1
the string before: 2345 level=2
the string before: 345 level=3
the string before: 45 level=4
the string before: 5 level=5
the string after: 5 level=5
the string after: 45 level=4
the string after: 345 level=3
the string after: 2345 level=2
the string after: 12345 level=1

参看第二版<代码>(>>( after)在你从休养职能返回时执行。

Answer 2

If you are not familiar with a recursion call stack, I would encourage you to look into it for fully understanding the print statements. Basically, each time azalt is being called recursively, it preserves the most recent line it executed and goes straight to the next call. When the next call returns, it executes the line right after it (keep in mind, it knows which line to execute because it is preserved in the stack). When it is done executing all the next steps, it returns.

电话: azalt(12345) [prints 12345, Next calls, the current calls on ack]

电话2:azalt(2345) [打印2345,下调,目前打脚印]

电话3:azalt(345) [打印345,下调,目前打脚]

第4号:azalt(45)[第45号,下调,目前呼吁打字]

电话5:azalt(5) [印数5,下电话:当前打字]

电话6:azalt(发泄) [恢复和从警钟中删除]

电话5:azalt(5) [现在印有5份,返回,从警钟中删除]

电话4:azalt(45) [现在印有45部,返回并搬出电线]

电话3:azalt(345) [现在印有345部,返回并拆除电话亭]

电话2:azalt(2345) [现在印有2345页的文字,返回并搬出电线]

call 1: azalt(12345) [now prints 12345, return and remove from the call stack]

希望这一帮助!

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