check a textboxcontent isnumeric or not

Question

how to check if the content of Textbox is numeric or not in C# ?

double montant = double.Parse(_controle.Text);
if ( || (double.Parse(_controle.Text) < 0))
{
    Declanche_Erreur = true;
    _controle.BackColor = System.Drawing.Color.White;
    break;
    return;
}
else
{
    Declanche_Erreur = false;
    _controle.BackColor = System.Drawing.Color.White;
}

Answer 1

You can use double.TryParse. If it succeeds, it will set montants value and return true

            double montant = -1;

            if (!double.TryParse(_controle.Text, out montant))
                {
                    Declanche_Erreur = true;
                    _controle.BackColor = System.Drawing.Color.White;
                    return;
                }
                else
                {
                    Declanche_Erreur = false;
                    _controle.BackColor = System.Drawing.Color.White;
                }