dongliang9682
dongliang9682
2009-07-23 15:22

Php for循环有2个变量?

已采纳

is it possible to do this? (here is my code)

for ($i = 0 ; $i <= 10 ; $i++){
  for ($j = 10 ; $j >= 0 ; $j--){
     echo "Var " . $i . " is " . $k . "<br>";
  }
}

I want something like this:

var 0 is 10

var 1 is 9

var 2 is 8 ...

But my code is wrong, it gives a huge list. Php guru, help me !!

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7条回答

  • dtysql0586 dtysql0586 12年前

    Try this:

    for ($i=0, $k=10; $i<=10 ; $i++, $k--) {
        echo "Var " . $i . " is " . $k . "<br>";
    }
    

    The two variables $i and $k are initialized with 0 and 10 respectively. At the end of each each loop $i will be incremented by one ($i++) and $k decremented by one ($k--). So $i will have the values 0, 1, …, 10 and $k the values 10, 9, …, 0.

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  • drl37530 drl37530 12年前

    If, as your code looks like, you have two values running the opposite direction you could simply substract:

    echo "Var " . $i . " is " . 10 - $i . "<br>";
    

    But I guess that's not really what you want? Also, be careful with the suggested comma operator. While it is a nice thing it can cause naughty side effects in other languages like C and C++ as PHP implements it differently.

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  • duanchi19820419 duanchi19820419 12年前

    To expand on the other (correct) answers, what you were doing is called nesting loops. This means that for every iteration of the outer loop (the first one), you were completing the entire inner loop. This means that instead of 11 outputs, you get 11 + 11 + 11 + ... = 11 * 11 outputs

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  • dongzhuang5741 dongzhuang5741 12年前

    You shouldn't be using two for-loops for what you'd like to achieve as you're looping 121 times total (11x11). What you really want is just to have a counter declared outside of the loop that tracks j, and then decrement j inside the loop.

    Edit: Thanks Gumbo for catching the inclusion for me.

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  • dongyu9850 dongyu9850 5年前

    I tried to get a start and end time and store in the database, given a start and end time, you loop through each time using two variables i&j

       $start = "09:00";
       $end = "18:00";
       $strEnTim = strtotime("10.00");
    
       $slotStart = strtotime($start);
       $slotEnd = strtotime($end);
       $slotNow = $slotStart;
    
       for( $i=$slotStart, $j=$strEnTim; $i, $j<=$slotEnd; $i+=3600,  $j+=3600) 
       {
            if(( $i < $slotNow) && ( $j < $strEnTim)) continue;
            Slot::create([
                'start_time' => date("H:i",$i),
                'end_time' => date("H:i", $j)
            ]);
       }
    
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  • dongxuanchao1425 dongxuanchao1425 6年前
    array_map(function($i) {
        echo "Var {$i} is ".(10-$i)."<br/>".PHP_EOL; 
    }, range(1,10));
    
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  • doumi2106 doumi2106 5年前

    You could also add a condition for the second variable

    for ($i=0, $k=10; $i<=10, $k>=0 ; $i++, $k--) {
        echo "Var " . $i . " is " . $k . "<br>";
    }
    
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