PHP 数字金额转换成英文金额

数据库存储的金额为阿拉伯数字，但产品需求中需要呈现给用户消费账单时带有英文的金额，于是调用此封装函数，可将阿拉伯数字金额转换成英文的金额。

<?php
echo( number_to_word( 150.10) );    //调用
function number_to_word( $num = '' )
{
    $num    = ( string ) ( ( int ) $num );
    if( ( int ) ( $num ) && ctype_digit( $num ) )
    {
        $words  = array( );
        $num    = str_replace( array( ',' , ' ' ) , '' , trim( $num ) );
        $list1  = array('','one','two','three','four','five','six','seven',
            'eight','nine','ten','eleven','twelve','thirteen','fourteen',
            'fifteen','sixteen','seventeen','eighteen','nineteen');
        $list2  = array('','ten','twenty','thirty','forty','fifty','sixty',
            'seventy','eighty','ninety','hundred');
        $list3  = array('','thousand','million','billion','trillion',
            'quadrillion','quintillion','sextillion','septillion',
            'octillion','nonillion','decillion','undecillion',
            'duodecillion','tredecillion','quattuordecillion',
            'quindecillion','sexdecillion','septendecillion',
            'octodecillion','novemdecillion','vigintillion');
        $num_length = strlen( $num );
        $levels = ( int ) ( ( $num_length + 2 ) / 3 );
        $max_length = $levels * 3;
        $num    = substr( '00'.$num , -$max_length );
        $num_levels = str_split( $num , 3 );
        foreach( $num_levels as $num_part )
        {
            $levels--;
            $hundreds   = ( int ) ( $num_part / 100 );
            $hundreds   = ( $hundreds ? ' ' . $list1[$hundreds] . ' Hundred' . ( $hundreds == 1 ? '' : 's' ) . ' ' : '' );
            $tens       = ( int ) ( $num_part % 100 );
            $singles    = '';
            if( $tens < 20 )
            {
                $tens   = ( $tens ? ' ' . $list1[$tens] . ' ' : '' );
            }
            else
            {
                $tens   = ( int ) ( $tens / 10 );
                $tens   = ' ' . $list2[$tens] . ' ';
                $singles    = ( int ) ( $num_part % 10 );
                $singles    = ' ' . $list1[$singles] . ' ';
            }
            $words[]    = $hundreds . $tens . $singles . ( ( $levels && ( int ) ( $num_part ) ) ? ' ' . $list3[$levels] . ' ' : '' );
        }
       
        $commas = count( $words );
       
        if( $commas > 1 )
        {
            $commas = $commas - 1;
        }
       
        $words  = implode( ', ' , $words );
       
        //Some Finishing Touch
        //Replacing multiples of spaces with one space
        $words  = trim( str_replace( ' ,' , ',' , trim_all( ucwords( $words ) ) ) , ', ' );
        if( $commas )
        {
            $words  = str_replace_last( ',' , ' and' , $words );
        }
       
        return $words;
    }
    else if( ! ( ( int ) $num ) )
    {
        return 'Zero';
    }
    return '';
}

function trim_all( $str , $what = NULL , $with = ' ' )
{
    if( $what === NULL )
    {
        //  Character      Decimal      Use
        //  "\0"            0           Null Character
        //  "\t"            9           Tab
        //  "\n"           10           New line
        //  "\x0B"         11           Vertical Tab
        //  "\r"           13           New Line in Mac
        //  " "            32           Space

        $what   = "\\x00-\\x20";    //all white-spaces and control chars
    }

    return trim( preg_replace( "/[".$what."]+/" , $with , $str ) , $what );
}

function str_replace_last( $search , $replace , $str ) {
    if( ( $pos = strrpos( $str , $search ) ) !== false ) {
        $search_length  = strlen( $search );
        $str    = substr_replace( $str , $replace , $pos , $search_length );
    }
    return $str;
}