C compiler error not all code paths return a value

Question

I m trying to write code that returns whether or not a given integer is divisible evenly by 1 to 20  but I keep receiving the following error       error CS0161   ProblemFive isTwenty int    not all code paths return a value   Here is my code    public static bool isTwenty int num        for int j   1  j  lt   20  j                  if num   j    0                        return false                    else if num   j    0  amp  amp  num    20                        return true

User · Answer

Have a look at this one  It is the Ternary operator in C     bool BooleanValue    num   3    0    true   false    This is just to show the principle  you can return True or False  or even integer or string  depending on the outcome of something on the left side of the question mark  Nice operator  this    Three alternatives together          public bool test1                         int num   21              bool BooleanValue    num   3    0    true   false              return BooleanValue                     public bool test2                         int num   20              bool test    num   3    0               return test              Even Shorter    public bool test3         int num   20      return  bool  num   3    0

User · Answer

Or Simply Do this Stuff   public static bool isTwenty int num       for int j   1  j  lt   20  j               if num   j    0                    return false                else if num   j    0  amp  amp  num    20                    return true                else           return false

User · Answer

The compiler doesn t get the intricate logic where you return in the last iteration of the loop  so it thinks that you could exit out of the loop and end up not returning anything at all   Instead of returning in the last iteration  just return true after the loop   public static bool isTwenty int num      for int j   1  j  lt   20  j          if num   j    0          return false              return true      Side note  there is a logical error in the original code  You are checking if num    20 in the last condition  but you should have checked if j    20  Also checking if num   j    0 was superflous  as that is always true when you get there

User · Answer

I like to beat dead horses  but I just wanted to make an additional point   First of all  the problem is that not all conditions of your control structure have been addressed  Essentially  you re saying if a  then this  else if b  then this  End  But what if neither  There s no way to exit  i e  not every  path  returns a value    My additional point is that this is an example of why you should aim for a single exit if possible  In this example you would do something like this   bool result   false  if conditionA       DoThings       result   true    else if conditionB       result   false    else if conditionC       DoThings       result   true     return result    So here  you will always have a return statement and the method always exits in one place  A couple things to consider though    you need to make sure that your exit value is valid on every path or at least acceptable  For example  this decision structure only accounts for three possibilities but the single exit can also act as your final else statement  Or does it  You need to make sure that the final return value is valid on all paths  This is a much better way to approach it versus having 50 million exit points

User · Answer

class Program       double   a   new double     1  3  4  8  21  38        double   b   new double     1  7  19  3  2  24        double   result        public double   CheckSorting                 for int i   1  i  lt  a Length  i                          if  a i   lt  a i - 1                   result   b              else                 result   a                    return result             static void Main string   args                Program checkSorting   new Program            checkSorting CheckSorting            Console ReadLine              This should work  otherwise i got the error that not all codepaths return a value  Therefor i set the result as the returned value  which is set as either B or A depending on which is true

User · Answer

I also experienced this problem and found the easy solution to be  public string ReturnValues         string  var          Setting an innitial value      if             Looking at conditions                var    true      Re-assign the value of  var            return  var     Return the value of var     This also works with other return types and gives the least amount of problems  The initial value I chose was a fall-back value and I was able to re-assign the value as many times as required

User · Answer

This usually happens to me if I misplace a return statement  for example    Adding a return statement  or in my case  moving it to correct scope will do the trick

User · Answer

You re missing a return statement   When the compiler looks at your code  it s sees a third path  the else you didn t code for  that could occur but doesn t return a value   Hence not all code paths return a value     For my suggested fix  I put a return after your loop ends   The other obvious spot - adding an else that had a return value to the if-else-if - would break the for loop   public static bool isTwenty int num        for int j   1  j  lt   20  j                  if num   j    0                        return false                    else if num   j    0  amp  amp  num    20                        return true                      return false     This is your missing statement

[c#] C# compiler error: "not all code paths return a value"

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