Thread: Compare integers in an array

Hello. I'm new to C programming and attending a web course. We learned about arrays but I still struggle to understand how to compare values in an array. Say I have

Code:

{2 4 6 1 5}

and I want to compare index 0 with index 1,2,3,4 not by typing

Code:

array[0]

and

Code:

array[1]

but

Code:

array[k] with array[?]

.

Thank you in advance, Mike

I'm going to assume that you're trying to compare "every element to every other element" or some such. This is a use case that occurs frequently in dealing with arrays.

To do this, you'll want two variables. Traditionally, these are i and j. When you get to a third variable, that will be k. (This comes from Fortran, where variable type (integer, real, etc) was determined by the first letter.)

Code:

extern SomeType a[];
extern size_t alen;

for (int i = 0; i < alen; ++i) {
    for (int j = i + 1; i < alen; ++j) {
        // do something with a[i], a[j]        
    }
}