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Comments on What might happen if I ignore warning?

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What might happen if I ignore warning?

+1
−2
#include <iostream>
using namespace std;

int linearSearch(int array[], int n, int key){
	for(int i=0;i<=n;i++){
		if(array[i]==key){
			return i;
		}
	}
}

int main() {
  int balance[] = {10,240,120,150,100};
  cout<<linearSearch(balance, sizeof(balance)/sizeof(balance[0]), 150);
  return 0;
} 

When executing the code I got an warning. Should I really care of warning? I got expected output. Although, I was thinking of warning. What might happen if I ignore warning?

test.cpp: In function ‘int linearSearch(int*, int, int)’:
test.cpp:10:1: warning: control reaches end of non-void function [-Wreturn-type]
   10 | }
      | ^

When I add return 0; at end of for loop I don't get the error anymore. The warning was saying that the linearSearch method (function) wasn't returning always. But, can warning crash my applications?

Replying to last edit of Alexei : My question was about any type of warning not only above one. Above one was just an example. Anyway, I got more accurate answer in the thread

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1 comment thread

Yes, it can crash, because this leads to undefined behaviour. Try to search for a number that's not i... (2 comments)
Yes, it can crash, because this leads to undefined behaviour. Try to search for a number that's not i...
hkotsubo‭ wrote over 2 years ago

Yes, it can crash, because this leads to undefined behaviour. Try to search for a number that's not in the array, what will it return? I've tested in a Ubuntu machine, with g++ (it returns 6) and clang++ (Illegal instruction error), but as all undefined behaviours, this can vary a lot. IMO, you should worry more about writing clear/semantic/correct code instead of "it works" code. Does it make sense to not return anything if an element is not found? Sometimes you "know" it won't reach the non-return point, but that's not your case - if the number is not in the array, it won't return anything (one common approach is to return an invalid index, such as -1, to indicate the "not found" situation - returning zero is wrong because it means that the element is in the first position). And the loop condition should be i < n, not <= :-)

hkotsubo‭ wrote over 2 years ago

Regarding warnings, they're usually meant to tell you "Hey, there's something strange here, you should take a look". You shouldn't ignore them, unless there's a very good reason - which is not the case of your code, IMO.