1. A method for structuring program code to implement program debugging of the program code using tracking of variables, said method comprising: determining, by a processor, a first variable to be tracked and a first expression associated with the first variable, said program code comprising the first variable and the first expression; said processor performing a reverse scanning of the program code to search for a first assignment expression within a first assignment statement that assigns a value of the first assignment expression to the first variable; in response to finding the first assignment expression via the reverse scanning, said processor inserting, into the program code after the first assignment statement, a first watch point for determining a true/false value of the first expression; and prior to said reverse scanning, said processor performing a forward processing of the program code to collect runtime information associated with a control flow for the first assignment statement to avoid an occurrence of an error, due to the control flow, during an automatic setting of the first watch point.