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Programming recap

Programming recap. Do you know these?. LOW LEVEL 1 st generation: machine language (110011) 2 nd generation: assembly language (ADD, SUB) HIGH LEVEL 3 rd / 4 th generation: E.g. Pascal, C++, Java. How about these?. Source code: original instructions

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Programming recap

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  1. Programming recap

  2. Do you know these? • LOW LEVEL • 1st generation: machine language (110011) • 2nd generation: assembly language (ADD, SUB) • HIGH LEVEL • 3rd / 4th generation: • E.g. Pascal, C++, Java

  3. How about these? • Source code: original instructions • Object code: machine language version • Compiling: converting from source to object • Linking: bring all data together before running • Executing: running the program • Maintaining: ensuring program continues to run

  4. Do these errors ring a bell? • Syntax error: error with the use of the language • Logic error: error when something is out of sequence or doesn’t make sense (e,g, sum = a * b) • Runtime error: error when program runs • Testing: checking for errors • Debugging: Fixing errors

  5. Types of statements • Assignment • Calculation • Input • Output • Looping • Selection/condition • Program header • Vat:= 0.15 • Vat:=price * tax • Read(age) • Write(age) • For age:= 1 to 5 do • While age<65 do • If age > 65 then • Program OLDAGE;

  6. Symbols symbolssymbols • ; means end of line • { } is used to put comments that are not a part of the program • := means equals • . Means end of program • > more than • < less than • <> not equal to • = is equal to • >= more than or equal to

  7. What are datatypes? • Integer – whole number (90) • Real – decimal number (9.67) • Char – single letter (n) • String – word (nine) • Array – a list

  8. Declaring an array • Declare an array named class that has 20 spaces and stores the names of persons • CLASS : array[1..20] of STRING; datatype Name of array Number of spaces

  9. Working with arrays • Output the fourth value in CLASS • Writlen(CLASS[4]); • Input a value into the 10th space in class • Readln(CLASS[10]); • Input the name “george” into the 8th position in CLASS • CLASS[8]:=“george”;

  10. Tracing a program – Jan 2013, #9 • Pascal • Sequence. • Output • The result is 12 • Set A = no error Set B = runtime error. Because num1 is 2.5. This is a real number.

  11. Boolean – ones and zeros! OR AND

  12. Documentation?? • External documentation • Use manuals • Installation procedures • Frequently asked questions • Internal documentation • Comments in your program • Indenting so your program is neat

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