Home/ Questions/Is there any solution for the not all code paths return a value in C# error?
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Juliette Courtois
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Asked: 2022-05-12T12:05:54+00:00 In:

Is there any solution for the not all code paths return a value in C# error?

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I am tired of fixing the problem: not all code paths return a value in C# in the csharp; even if I get the reference from another forum, it still returns an error:

error CS0161: 'ProblemFive.isTwenty(int)': not all code paths return a value

To identity the problem, I will show you the detail here:

public static bool isTwenty(int num)
 {
  for(int j = 1; j <= 20; j++)
  {
  if(num % j != 0)
  {
  return false;
  }
  else if(num % j == 0 && num == 20)
  {
  return true;
  }
  }
 }

How do I do that? Could you support me in improving this problem?

♦ Suggestions of ITtutoria Team

You are missing a return assertion.

The compiler will look at your code and see a third path (the else that you didn’t code) that could exist but does not return any value. not all code paths return a value is the result.

My suggestion was to add a return value to the if-else-if after your loop ends. Another obvious spot is adding a else with a return value in the if-else-if. This would break the for loop. 

public static bool isTwenty(int num)
{
    for(int j = 1; j <= 20; j++)
    {
        if(num % j != 0)
        {
            return false;
        }
        else if(num % j == 0 && num == 20)
        {
            return true;
        }
    }
    return false;  //This is your missing statement
}
not all code paths
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2 Answers

  1. Best Answer
    Expert

    The cause: You are missing a return assertion. The compiler will look at your code and see a third path (the else that you didn’t code) that could exist but does not return any value. not all code paths return a value is the result.

    Solution: My suggestion was to add a return value to the if-else-if after your loop ends. Another obvious spot is adding a else with a return value in the if-else-if. This would break the for loop.

    public static bool isTwenty(int num)
{
for(int j = 1; j <= 20; j++)
{
if(num % j != 0)
{
return false;
}
else if(num % j == 0 && num == 20)
{
return true;
}
}
return false; //This is your missing statement
}
    • 18

  2. The compiler does not understand the complex logic of returning in the last loop iteration. It thinks you could exit the loop without ever returning anything.

    Do not return in the previous iteration. Instead, return true after the loop. 

    public static bool isTwenty(int num) {
 for(int j = 1; j <= 20; j++) {
 if(num % j != 0) {
 return false;
 }
 }
 return true;
}

    Side note: There is a logic error in the original code. While you are checking num == 20 in this last condition, it is important to check j == 20. You should also check if num % j == 0 is superflous. This is because it is always true once you reach there.

    • 5

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