I am doing Cs50 Harvard University online and I'm on week 3 but while watching the video I noticed that I iterations and loops seem the same, as they repeat things over and over. But there must be a difference or else they wouldn't have two names for the same thing. No matter how many times I re-watch the video I can't find a difference. Please help me understand.
4 Answers
"Loop" refers to language constructs that are used to repeatedly execute some code. (for loops, while loops, etc.)
"Loop" can also refer to code being executed repeatedly. (e.g. "It's stuck in a loop.")
Iterating is the process of doing something repeatedly. (e.g. "This loop iterates over the elements of the array.")
An iteration is a single pass of a loop. (e.g. "In the first iteration of that for loop, i will be 0.")
Usually "loop" refers to the code and "iteration" refers to the conceptual process of repeating some steps. In this case, they are more or less the same. Additionally, you could use "iteration" to refer to a single repetition within a loop which gives it a different meaning.
A case example for the first usage of "iteration" would be:
You can print a linked list either by using iteration or recursion. If you use iteration, simply create a while-loop that propagates a "current" node through the list and stops when it becomes NULL.
And an example refering to specific repetitions:
The following loop outputs numbers 1 to 10 in reverse order. At the
k-th iteration,10-k+1is printed:
for (i=10; i>=1; i--){
printf("%d\n", i);
}
A loop in code is a combination of 3 things.
- a conditions or a break moment. (it wont stop out of it self)
- a loop paremeter, index
- a repeatable to-do list
Than you talking about iterations. A iteration is just 1 instance of the loop. So the first time you loop is running your are on you 0 instance / iteration. your index is refering almost every time to your instance / iteration.
https://codingbat.com/doc/java-for-while-loops.html
https://www.programiz.com/c-programming/c-for-loop
Also iterations are not based on conditions but event based.
I hope I answered your question, reply if more info is needed.
That's how I would define it:
"Loop" - A control flow statement that iterates the code in the loop's body dependent upon a provided loop condition. It is a language construct and in C we have three kinds of these constructs: for, while and do-while.
"Iteration" - One specific walkthrough of the code inside of the loop's body after the first walkthrough. In other words, a single repetition of the execution of the loop body's code.
When doing looping/iterating (as verb they can be seen equal indeed), you repeat over the code in the loop's body. Every single repetition is an iteration.
A loop's purpose is the capability to do iterations. Without being able to do iterations the loop construct is useless.
So, both terms are closely related, but not the same.
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