颜色交替问题

Question

I'm having trouble with the script below. Currently it's just alternating through the colors for the first 4 $i items. The rest is echo'ed in black. How do I make it loop through the colors for all the $i values?

<?php 
$colors = array('lightgreen','lightblue','orange','red'); 

for($i = '0'; $i < '50'; $i++) { 
 echo " <span style='color: ".$colors[$i].";'><span style='font-family: Webdings; font-size: 30px; '>&#".$i."</span>&#38;&#35;".$i.";</span>"; 
} 
?>

Answer 1

您可以为此使用模运算符（除法后的余数）：

echo " <span style='color: ".$colors[$i % 4] ...

Answer 2

[EDIT : based on jeroen' answer which is better than mine] :

you have 4 colors and you loop 50 times without checking if any color is available. You should add a variable to check the number of color and set it to 0 when there are no more available :

<?php
$colors = array('lightgreen','lightblue','orange','red');
$nbColors = count($colors);

for($i = '0'; $i < '50'; $i++) {
    echo " <span style='color: ".$colors[$i % $nbColors].";'><span style='font-family: Webdings; font-size: 30px; '>&#".$i."</span>&#38;&#35;".$i.";</span>";
}

That allows you to add colors in your initial array without breaking the code.

Answer 3

Your array of colours only has four items in it. When $i is 3, $colors[$i] will pull out red as it's the fourth one along (remember the array is zero based). So when $i is equal to 5 there is no colour in the array in that position.

<?php 
$colors = array('lightgreen','lightblue','orange','red'); 
//Create a variable to store the colour index
$colorPos = 0;

for($i = '0'; $i < '50'; $i++) { 
    echo " <span style='color: ".$colors[$i].";'><span style='font-family: Webdings; font-size: 30px; '>&#".$i."</span>&#38;&#35;".$i.";</span>"; 
    $colorPos++;
    if($colorPos == 4) $colorPos = 0;
} 
?>

You could also look in to using next() and reset() on the array: http://php.net/manual/en/function.next.php

Answer 4

Thank you to everybody. Based on your suggestions I ended up doing like this :

<?php
$colors = array('lightgreen','lightblue','orange','red','magenta');

for($i = '0'; $i < '50'; $i++) {
 echo " <span style='color: ".$colors[$i % count($colors)].";'><span style='font-family: Webdings; font-size: 30px; '>&#".$i."</span>&#38;&#35;".$i.";</span>";
}
?>