2.5 - Languages & Translators

• Uses syntax similar to a natural human language to make it easier to understand and use • Must be translated into machine code before it can be run

• More easily written and understood by humans • Portable (can be run on many different CPUs) • Slow to run

Does not closely resemble a natural human language making it harder for humans to understand and use

-Low-level languages are easier to optimise -Low-level languages allow the user to directly manipulate memory -Low-level languages are specific to particular CPUs

• Machine Code • Assembly Language

Binary

Uses specialised command mnemonics to perform actions

Computers are made up of millions of transistors (switches) which can only represent two states (ON and OFF)

• Interpreter • Compiler

Execution method: - Interpreters translates the source code into machine code line-by-line - Compilers translate all the source code into machine code in one go and produce an executable file Execution speed: - Interpreters are slower than compilers because the code must be reinterpreted each time the program is run - Compilers can produce much more efficient code than interpreters, making the compiled programs run faster Complexity: - Interpreters are smaller, simpler programs - Compilers are large, complex programs Error reporting: - Interpreters report errors to the user immediately and stops translation - Compilers produces all the errors in an error file at the end of compilation Repetition: - Interpreters must reinterpret the program every time - Compilers doesn’t need reinterpretation, but must be re-compiled after changes are made

• Produces an executable program: No need to repeat this process more than once per version of the software • Hides the source code from the end user: Protects developers’ intellectual property • Source code not needed afterwards • Fast to execute afterwards

-Very slow compilation process: This can slow down development if many small changes need to be made • Errors only shown right at the end

-Interpreted languages are ‘portable’: This means that they can be run on many different types of CPU as long as there is an interpreter available for the platform - Errors discovered straight away - Good for small changes

• Source code needed to run • Slower to execute

Provides programmers with tools to help create programs

• Editor • Error diagnostics and debugger • Run time environment • Translator • Break point • Variable watch/watch window • Trace

Allows a programmer to enter and edit source code - Features may include: - Automatic formatting - Automatic line numbering - Automatic colour coding - Statement completion.

Allows the programmer to select a specific line and the program displays variable values at that point - a process called single-stepping

Displays the current value of a selected variable which can be watched line-by-line to see how the value changes

Logs the values of variables and outputs of the program as the code is executed line by line

• Displays information about an error when it occurs (when the program fails to compile or run), such as the line it occurred on and the error type • The debugger helps locate, identify and rectify errors in a program • May also suggest solutions to help the programmer find and fix the error

Allows user to run and test the program to determine if there are any logic errors