how to compare real valued output to the target values having 0 and 1

hello everyone

my question may be stupid but i really want to know that

in backpropogation algorithm i am getting real valued output at output layer and that should be compared with target output having 0 and 1

in testing phase how we can decide that actual output(real value) is same/different from target one , is there any thresholding stratagy to decide that ?