Thread: need help understanding basic arrays

Hey everyone..

So i'm adding arrays to the already long-enough list of C concepts that i don't understand. I looked at the tutorial on this site and i've googled for info on arrays; nothing i have read has helped me understand any better so i was hoping someone here could maybe explain what's happening in layman's terms.

To be clear, this is not homework, this is just an example practice question that i don't quite understand..

What is the output of the following program?

Code:

Int main() {
Int array[5] = {3, 6, 2, 7, 1}
Int I;
 
For (i=0; i<4; i++)
               Array[i] = array[i] + aray[i+1]
For (i=0; i<5; i++)
               Printf(“%d”, array [i]);
Return 0;
}

now i put this into codeblocks and the output was '98981.' However, i don't understand how. I guess my real question is this: What's going on within the for loops?

i do understand better now; I mean, i see how you got the output, at least. i guess i was confusing myself after looking at i=0 so my thought process was something like this: since i=0 then 0+0+1=0...

i know bigH. i was rushing sorry lol. but rest assured i fixed it in codeblocks.. i copied and pasted this from a powerpoint.

for more clarification.. here's another example that i can't figure out with the same logic because it is a different type of problem..

Code:

int main() {
               int a[] = {8, 1, 6, 3, 5, 7, 2, 4, 10, 9};
               int i;
 
                              for (i=0; i<10; i++)
                              a[i] = a[a[i]-1];
 
               for (i=0; i<10; i++)
                              printf("%d ", a[i]);
 
                              return 0;
}

i'm not entirely sure what

Code:

a[i] = a[a[i]-1];

is asking.

i see. so then the next value would be a=1, 1-1=0, and 8 is at the 0 value but it has been replaced by 4? so the second value is 4? is that how it works?

well thanks for the help. i'm pretty sure i understand it now. i'm assuming things might get a little complicated with all the numbers changing so i'll just have to keep track of everything on paper.

i appreciate it