Understanding of php recursive code

{Code ...} the output result is as follows: {code ...} my doubt is that when $ count is added to 10, it will not call itself, then it will run the following code $ count -- and the output will end, but why is it still running nine times.

function test(){    static $count = 0;    $count++;    echo "-- ".$count." --\n";    if ($count < 10) {        test();    }    $count--;    echo "## ".$count." ##\n";}test();

The output is as follows:

-- 1 ---- 2 ---- 3 ---- 4 ---- 5 ---- 6 ---- 7 ---- 8 ---- 9 ---- 10 --## 9 #### 8 #### 7 #### 6 #### 5 #### 4 #### 3 #### 2 #### 1 #### 0 ##

My question is when$countAfter adding 10, it will not call itself, so it will run the following code$count--Then the output ends, but why is it still running nine times.

Reply content:

function test(){    static $count = 0;    $count++;    echo "-- ".$count." --\n";    if ($count < 10) {        test();    }    $count--;    echo "## ".$count." ##\n";}test();

The output is as follows:

-- 1 ---- 2 ---- 3 ---- 4 ---- 5 ---- 6 ---- 7 ---- 8 ---- 9 ---- 10 --## 9 #### 8 #### 7 #### 6 #### 5 #### 4 #### 3 #### 2 #### 1 #### 0 ##

My question is when$countAfter adding 10, it will not call itself, so it will run the following code$count--Then the output ends, but why is it still running nine times.

Let's take a look at the entire execution process when $ count is less than 2:

1. Change less than 10 to less than 2:

 function test()    {        static $count = 0;            $count++;        echo "-- ".$count." --\n";        if ($count < 2) {            test();        }        $count--;        echo "## ".$count." ##\n";    }

2. Replace the recursive test () in the lower than 2 with the code in the function body:

function test(){    static $count = 0;   // line 1    $count++; // line 2    echo "-- ".$count." --\n"; // line 3    if ($count < 2) { // line4        static $count = 0;        $count++; // line 5        echo "-- ".$count." --\n";// line 6        if ($count < 2) {// line 7            test();        }        $count--;// line 8        echo "## ".$count." ##\n";// line 9    }    $count--;// line 10    echo "## ".$count." ##\n";// line 11    }

3. After test () is called

test()

4. The detailed execution process is as follows:

4.1 for the first time, line 1: $ count = 0; 4.2 After line 2 is executed, $ count = 1; 4.3 will output in line 3: ** -- 1 -- ** 4.4 and then execute line 4. Because $ count <2 is true; 4.5, line 6 will output the result after line5 is executed and changed to 2 4.6: ** -- 2 -- ** 4.7 then goes to line 7. Because $ count = 2, after line 8 4.8 line 8 is executed directly at no less than 2, $ count becomes 1, then execute line 9 4.9 in line 9 and the output will be: ** #1 # ** 4.10 then execute line 10, $ count minus 1, the value is 0 4.11. Therefore, the output is ** #0 # ** In line 11 ##**

5. Conclusion:
When we assume that $ count is less than 2, we can see in the detailed execution process above:
Test () is executed twice in total,
Output result:
-- 1 --, -- 2 --, #1 ##,## 0 ##
At this time, we will try again to reduce $ count to 10, which will easily explain the landlord's questions.
I don't know if it helped you. Contact us if you have any questions.

No more than 9 times,testThe function runs only 10 times. However, each function has two outputs, so a total of 20 outputs are performed.

If there is no return, it will not stop, and it will continue to be executed after it is called.

Because when$count= 10, the code is still executed. You can write it like this.

function test(){    static $count = 0;    $count++;    echo "-- ".$count." --
";    if ($count < 10) {        test();        $count--;        echo "## ".$count." ##
";    }}test();

@ Phping: This is my understanding of recursion. It is similar to yours.

Function test () {static $ count = 0; // initialize the static variable $ count ++; // $ count = 1; echo "--". $ count. "-- \ n"; // output 1 if ($ count <3) {// 1 less than 3 is true static $ count = 0; // initial $ count ++; // $ count = 2; echo "--". $ count. "-- \ n"; // output 2 if ($ count <3) {// 2 less than 3 is true static $ count = 0; // initial $ count ++; // $ count = 3 echo "--". $ count. "-- \ n"; // output 3 if ($ count <3) {}// 3 not less than 3 is false $ count --; // $ count = 2; echo "##". $ count. "##\ n"; // output after subtraction 2} $ count --; // $ count = 1 echo "##". $ count. "##\ n"; // output after subtraction 1} $ count --; // $ count = 0; echo "##". $ count. "##\ n"; // output 0} test () after subtraction ();

Final output

-- 1 ---- 2 ---- 3 --## 2 #### 1 #### 0 ##