Thinking Python: Chapter 1 The way of the program

Thinking Python: Chapter 1 The way of the program

1. 1.1 The Python programming language

   • Languages
     • High level languages
       • C, C++,C#...
       • Mostly cannot be run by computers so they need to be processed first which takes time.
       • Needs an interpreter or a compiler to be used.
         • A compiler converts the whole of it before the program starts.
         • the processor converts it from high level to low level bit by bit.
     • Low level languages
       • Can be run by computers

2. 1.2 What is a program?

   • 1.5 The first program
     • Normally the first program you write in a new language is for it to output the message Hello World!
   • A program is a series of instructions which tells the computer what to do. This can be anything from doing a maths equation to changing data in a spreadsheet.
     • The program does this by using instructions.
       • Maths: The proses where it does maths E.G. 1+1=2
       • Repetition: where the program is repeated.
       • Input: the data coming in from a n input device E.G. Keyboard or gaming controller.
       • Output: the image or data that is outputted from the program.
       • Conditional execution: the program will only do something if the right specifications are met.

3. 1.3 What is debugging?

   • 1.3.1 Syntax errors
     • A Syntax error is were the structure of the program is wrong so it can't start. E.G. spelling mistakes, not ending a command properly...
   • 1.3.2 Runtime errors
     • A Runtime error is where your program comes upon an error after it has started, these are normally rare (more so in simple programs).
   • 1.3.3 Semantic errors
     • Systematic errors are were the program does as you have told it but you wanted to do something different. E.G. spinning the camera around the point (0,0) but it spins around the point (4,8).
   • 1.3.4 Experimental debugging
     • Experimental debugging is where you use clues to find the problem, then you experiment different forms of code to try and fix the bug.
     • People also view debugging as part of the process of programing.
   • 1.6 Debugging
     • People respond to computers the same way as they do with people E.G. when a computer is being slow calling it a stupid thing and calling it idiotic. (Taken from my siblings).
   • Debugging is the process of tracking down errors (Bugs) in your code/ program.
     • Bugs in computing are called that because in an early computer the operators traced an error to a moth that was trapped inside the computer.

4. 1.4 Formal and natural languages

   • Natural languages
     • A natural language is a language spoken by people E.G English, German... These are natural because they evolved, people try and put restraints on them but they still evolve even if we teach the rules and regulations of using the language it changes, for example how much english has changed over the centuries and even how much it changes year to year.
   • Formal languages
     • Formal languages are languages that have been designed by people not made by people, these languages do not change. For example a formal language is Maths because it does not change this is the same in a computer language because they don't change. The computer cannot change the language and if you try to the computer will not understand you.

5. 1.7 Glossary

   • object code: The output of the compiler after it translates the program.
   • executable: Another name for object code that is ready to be executed.
   • prompt: Characters displayed by the interpreter to indicate that it is ready to take input from the user.
   • syntax: The structure of a program.
   • semantics: The meaning of a program.