如何在字符串中间添加内容？

Here is my PHP code:

foreach ( $sums as &$sums_value ) {
    if ( !empty($sums_value) ) { 
        $sums_value = sprintf("%+d",$sums_value);
    }
} unset($sums_value);

$sums contains some [positive or negative] numbers. Here is an example of $sums's output:

/*
array (
    [today] => +24
    [yesterday] => -6
    [in last week] => 0
    [in last month] => 9
)

And I use it like this: (I generate a HTML)

$date = array ('today', 'yesterday', 'in last week', 'in last month');
foreach( $date as $item ) {
    $html .= '<span>'.$sums[$item].'</span>';
} echo $html;

/* output:
   <span>+24</span><span>-6</span><span>0</span><span>9</span>

Ok, all fine.

Well what's my question? It's about coloring. I want to set:

• red color to negative numbers
• green color to positive number
• black color to zero number

So I want this output:

<span style="color:green">+24</span><span style="color:red">-6</span><span style="color:black">0</span><span style="color:green">9</span>

As you see, I've added a style="color:????" property to all those <span>s which is dynamic. I mean that color depends on the number. How can I do that?

You can just test the sum in the loop:

$date = array ('today', 'yesterday', 'in last week', 'in last month');
foreach( $date as $item ) {
    $sum = $sums[$item];
    $color = '';

    if ($sum < 0) {
        $color = 'red';
    } elseif ($sum > 0) {
        $color = 'green';
    } else {
        $color = 'black';
    }

    $html .= '<span style="color:'.$color.';">'.$sums[$item].'</span>';
} echo $html;

simple php will do

echo 'style="color:';
if($sums[$item] == 0){ 
  echo 'black';
}
else if($sums[$item] > 0){
  echo 'green';
}
else{ 
  echo 'red';
}
echo '"';

In your foreach you need to add an if statement.

foreach( $date as $item ) {
    If($item = 0){
          $html .= '<span style="color:black">' . $sums[$item] . '</span>';
    }else if($item>0){
           $html .= '<span style="color:green">' . $sums[$item] . '</span>';
    }else{
            $html .= '<span style="color:red">' . $sums[$item] . '</span>';
    }
} 

I think you can do it without PHP. only CSS3

but if you want use php. Take a look on example

    function getColor($number) {
        if ($number == 0) {
             return 'black';
        } 
        if ($number > 0) {
             return 'green';
        } 
        if ($number < 0) {
             return 'red';
        } 
    }

    $date = array ('today', 'yesterday', 'in last week', 'in last month');
    foreach( $date as $item ) {
        $html .= '<span style="color:' . getColor($sums[$item])  . '">'.$sums[$item].'</span>';
    } echo $html;