cs

cs

1. High Level Language

   • o Designed to resemble a natural language such as English
   • o Easier for people to read and understand
   • o Likely to be fewer errors due to the ease of use
   • o Uses commands that perform complex instructions
   • o Can not be executed by a CPU - Requires translation into machine code
   • o Examples: Python Scratch

2. Low level language

   • o Uses the instruction set of a CPU
   • o Does not resemble natural language
   • o Is hard for people to understand and read
   • o Harder to find and correct errors
   • o Executed directly by the CPU, so can be made extremely efficient
   • o Examples: Little Man Computer Assembly Machine Code

3. Programme construction

   • Assemblers translate assembly language to machine code o Each operator and operand is replaced with its binary equivalent o No need for analysis of code or complex function creation
   • Compilers and Interpreters translate high level code to machine code o Complex translation each line of high-level code can require many machine code instructions
   • Compilers: o Translate the high-level code all at once to produce a machine code file o This machine code file (for example a .exe file) can be distributed and executed on compatible computers o Programs can be distributed without releasing the source code harder for competitors to copy their code o Machine code files are fast to execute
   • Interpreters: o Do not create an executable file they execute the source code by translating and executing one line at a time o The source code is distributed and executed by the user o Execution is slower, as the translation must take place before each line can run o Programs will run on any computer with the interpreter, no need to compile multiple versions o Easier to find runtime errors, as the location of the error can be shown

4. errors

   • syntax: Occurs when text that is not valid code is found
   • Runtime error: Occurs when the program tries to perform an impossible operation
   • Logical: Program executes and exits with no errors, but the program has not done what was expected o Hard to detect and fix as no errors are produced
   • Linking error: occurs when programme tries to import something from a file that doesnt exist

5. software tools

   • Trace A log can be created of user inputs, variable changes and other events This log can be consulted to identify where logic errors are occurring
   • o Break Point Breakpoints can be inserted at points in the code Execution will pause at these break points allowing the developer to analyse the programming using the following tools
   • o Variable Watch Inspecting the contents of each variable can make it easier to see where something has gone wrong
   • The exact contents of memory locations within the computer can be displayed while the program runs This can help with developing lower level programs o
   • Error Diagnostics Errors such as syntax errors can be dealt with by the IDE The location of the syntax error can be highlighted on the fly, like spell-checking in a word processor