| Keyword | Definition |
|---|---|
| Syntax | The rules that govern the tokens that make up a computer language. Can be defined using EBNF |
| Selection | Choosing actions to take (or statements to execute) based on criteria |
| Nesting | When statements or expressions are inside the scope of other statements or expressions |
| Iteration | Repeating a process, often with actions being taken in each step, and often with certain variables being incremented on each step |
| Definite Iteration | Iteration whereby the number of times to be repeated is known prior to iteration. |
| Indefinite iteration | Iteration whereby the number of times to be repeated is dependent upon certain criteria being met |
| Loop | The actions of a process which repeats a certain number of times |
| Sequencing | The order of the instructions within a program. If the instructions are executed in the wrong order, there may be undesired behaviour |
Here is some python code which demonstrates code which executes depending on certain conditions
age=int(input("Age: "))
if age<16:
print("You are too young to drive")
elif age>=16:
print("You are old enough to ride a motorcycle")
elif age>=70:
print("You need to requalify to drive a car")
else:
print("You are able to drive in a license")
Not python, but many languages have switch .. case statements which can achieve the same functionality, but with different (cleaner in some cases) syntax.
In the example given above, rewriting as a switch .. case would be very verbose since you would have to hardcode every single case (that’s over 70 cases). Here is an example where rewriting as switch .. case actually is better:
if x==5:
# do specific thing
elif x==10:
# do specific thing
elif x==13:
# do specific thing
elif x==28:
# do specific thing
elif x==234:
# do specific thing
else:
# do specific thing
This can be written in C# using a switch .. case statement like so:
switch(x){
case 5:
// do specific thing
break;
case 10:
// do specific thing
break;
case 13:
// do specific thing
break;
case 28:
// do specific thing
break;
case 234:
// do specific thing
break;
default:
// do specific thing
break;
}
Its an alternative syntax - may be more intuitive or cleaner in some cases.