procedure binsrch (a: elementlist; x: element; var n,j: integer);
{search the sorted array a[1..n] for x}
initialize lower and upper
begin
    while there are more elements do
    begin
        let a[mid] be the middle element;
        case compare (x, a[mid]) of
             '>': set lower to mid + 1;
             '<': set upper to mid - 1;
             '=': found x;
        end; {of case }
    end; {of while }
    not found;
end ;{of binsrch}