Programming Constructs

Programming Constructs

1. Assembler

   • Converts the low level assembly programming language into machine code
   • The assembler does this by converting the one-word assembly instructions into an opcode, e.g. converting AND to 0010. It also allocates memory to variables, often resulting in an operand.

2. Interpreter

   • Converts code one line at a time, into machine code and executes it.
   • Before high level programming languages can be run, code is converted by an interpreter, one line at a time, into machine code, which is then executed by the CPU.

3. Compiler

   • Converts high level programs into machine code for execution at a later time
   • The entire program is compiled at the same time, not one line at a time

4. Programming Errors

   • Syntax
     • Occurs when a command doesn't match the correct syntax dictionary and therefore doesn't compile at run time (where the error occurs)
       • E.g a spelling mistake like- A ADN B ; where it should be: A AND B
   • Runtime
     • Occurs when the program is running therefore is difficult to foresee until the program is run
       • E.g the program requests more memory before the program is compiled therefore the program will crash
   • Logical
     • Causes the program to output incorrect data
       • E.g an algorithm outputting ages but outputs negative numbers
   • Linking
     • Occurs when a programmer calls a function within a program and the correct library has not been linked to that program
       • When a program that calculates square root doesn't use the square root function
   • Truncating
     • When a number is approximated to a whole number/tenth/hundredth which is closer to zero
   • Rounding
     • When a number is rounded to the nearest whole number to help the program run smoother
       • E.g 34.4 to 34

5. High level language

   • Easier to use
   • Closer to the human language
   • Can run more complex programs

6. Low level language

   • Closer to machine code
   • Not as fast as High level language

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