Interpreter:

1. The syntax of each instruction is checked as it is entered.
2. Instructions that contain syntax errors are corrected and reentered.
3. Instructions without errors are executed immediately.
4. No object program is produced.

1. A structure chart can represent an entire program with modules whereas a flowchart can represent a module in a program.
2. In structure chart, rectangles are used to represent modules whereas in flowchart terminal, process, input/output, flowline, connector, decision etc outlines are usually used.

1. They are easy to learn, the resulting programs are generally easy to understand and modify.
2. Unlike low-level language, programs written in high-level language for one computer can usally be used on another computer with minor modifications.

After coding the program, programmer is needed to check if there is any syntax error or logic error. If there is no syntax error, programmer then look for logic error with some testing data and refine their code until expected output. The process of detecting errors is called debugging and testing.

Top-down programming:
1. The top-down approach has evolved as a useful technique in planning a modular program. 
2. In top-down programming we first define the main program module, which initiates program execution, calls other modules to perform specific functions, and then terminates execution.