"tryparse / parse like" pattern: best proceed exercise it

this doubt follow-up . xxx() tryxxx() settlement something unequivocally useful libraries. i am wondering best proceed offer both implementations but duplicating code.

what best:

public int dosomething(string a)
{
     // competence pitch an exception
}
public bool trysomething(string a, out result)
{
    try
    {
        outcome = dosomething(a)
        relapse true;
    }
    locate (exception)
    {
        relapse false;
    }

or

public int dosomething(string a)
{
     int result;
     (trysomething(a, out result))
     {
         relapse result;
     }
     else
     {
         pitch exception(); // exception?
     }
}
public bool trysomething(string a, out result)
{
    //...
}

i'd instinctively assume initial instance some-more repremand (you know accurately difference happened), nonetheless couldn't try/catch too expensive? there proceed locate difference second example?