Why this is giving error? https://ide.codingblocks.com/s/339220 https://leetcode.com/explore/featured/card/fun-with-arrays/527/searching-for-items-in-an-array/3250/ Why this is giving error? Please tell asap

Why this is giving error?

Why this is giving error? Please tell asap.

Please tell why I face a lot of issues while creating doubts.