PHP Adding large numbers PHP big homework PHP braces PHP large files

<code><span><span><?PHP</span><span>$a</span> = <span>'234567890'</span>;
    <span>$b</span> = <span>'111111111111101'</span>;
    <span>$m</span> = strlen(<span>$a</span>);
    <span>$n</span> = strlen(<span>$b</span>);
    <span>$num</span> = <span>$m</span>><span>$n</span>?<span>$m</span>:<span>$n</span>;
    <span>$result</span> = <span>''</span>;
    <span>$flag</span> = <span>0</span>;
    <span>while</span>(<span>$num</span>--){
        <span>$t1</span> = <span>0</span>;
        <span>$t2</span> = <span>0</span>;
        <span>if</span>(<span>$m</span>><span>0</span>){
            <span>$t1</span> = <span>$a</span>[--<span>$m</span>];
        }
        <span>if</span>(<span>$n</span>><span>0</span>){
            <span>$t2</span> = <span>$b</span>[--<span>$n</span>];
        }
        <span>$t</span> = <span>$t1</span>+<span>$t2</span>+<span>$flag</span>;
        <span>$flag</span> = <span>$t</span>/<span>10</span>;
        <span>$result</span> = (<span>$t</span>%<span>10</span>).<span>$result</span>;
    }
    <span>echo</span><span>$result</span>;
    <span>echo</span><span>"\r\n"</span>;
    <span>echo</span><span>$a</span>+<span>$b</span>;

<span>?></span></span></span></code>