Wins the offer (PHP version rewritten) ---- string

/ ** 
* replace spaces with each string "% 20 is" 
* 
* @param $ String String 
* (must be greater than the string length after replacement) @param $ length character array length 
* / 
function ReplaceBlank ($ String, $ length) { 

    IF ($ $ String length == null || <= 0) { 
        return 0; 
    } 

    $ orginalLength = 0; 
    $ numberOfBlank = 0; 
    $ I = 0; 
    the while ($ String [$ I]! null =) { 
        ++ $ orginalLength; 
        IF (String $ [$ I] == '') { 
            ++ $ numberOfBlank; 
        } 

        ++ $ I; 
    } 

    $ orginalLength the newLength = $ 2 + $ * numberOfBlank; 
    IF (the newLength $> length $) { 
        return 0; 
    } 

    $ = $ indexOfOrginal orginalLength; // 14
    $indexOfNew = $newLength;
    while ($indexOfOrginal >=0 && $indexOfNew >$indexOfOrginal){
        if ($string[$indexOfOrginal]==' '){
            $string[$indexOfNew--]='0';
            $string[$indexOfNew--]='2';
            $string[$indexOfNew--]='%';
        } else{
            $string[$indexOfNew--] = $string[$indexOfOrginal];
        }
        --$indexOfOrginal;
    }

    return $string;
}

print_r(ReplaceBlank('we are family! ',30));

方法二：利用PHP内置函数str_replace

function replaceSpace($str)
{
    // write code here
    return str_replace(" ","%20",$str);
}