How to get sum of array elements excluding the numbers between a and b using c language?

Question

where a and b are some elements of array. Have to find sum of array excluding the number between the a and b.

Answer 1

store the two numbers, iterate through the array and add the numbers. then, when you find number a, stop adding the numbers until you reach b, then you can start adding them again

Answer 2

what if user inputs b first then a. Then this program won't work.