将十六进制数转换为字符串 - Convert an hexadecimal number to a string

Convert an hexadecimal number to a string

我正在尝试将十六进制数转换为正确的css格式：

$white = hexdec('#ffffff');
//Loops for a bunch of colours
for( $i = 0 ; $i <= $white ; $i=$i+5000 ) 
{
    //set default css background-color property
    $backgroundValue = dechex( $i );
    //if there are less of 7 characters (ex. #fa444, or #32F, ...)  
    if( $numLen = strlen( dechex( $i )) < 7 ) 
    {
        //insert (7 - numbers of characters) number of zeros after # 
        for ( $j = 0 ; $j < 7 - $numLen ; $j++ )
            $backgroundValue = strtr( $backgroundValue, '#', '#0' );                
    }
    //echo each div with each background-color property. 
    echo '<div class="colour" style="width: 10%; float: left; background: '.$backgroundValue.';">'.dechex($i).'</div>';
}

但这行不通。我怎样才能将十六进制数变成字符串，例如：#FFFFFF.

更新：

问题是我没有将#传递给字符串的开头：$backgroundValue = '#'.dechex( $i ); .

此代码工作正常：

        $white = hexdec('#ffffff');
        for( $i = 0 ; $i <= $white ; $i=$i+10000 ) 
        {
            $backgroundValue = '#'.dechex( $i );
            $numLen = strlen( dechex( $i ));
            if( $numLen < 6 ) 
            {
                for ( $j = 0 ; $j < (6 - $numLen) ; $j++ )
                    $backgroundValue = str_replace( '#', '#0', $backgroundValue );              
            }
            echo '<div class="colour" style="width: 10%; float: left; background: '.$backgroundValue.';">'.$backgroundValue.'</div>';
        }

为什么不简单地使用 str_repeat ？

$end = 0xffffff;
for ($i = 0; $i < $end; $i += 5000) {
    $color = (string) dechex($i);
    $backgroundValue = '#' . str_repeat('0', 6 - strlen($color)) . $color;
    echo '<div class="colour" style="width: 10%; float: left; background: '.$backgroundValue.';">'.dechex($i).'</div>';
}

您也可以使用 Sprintf

$backgroundValue = sprintf('#%06x', $i);