Home/ Questions/Is there any solution for the warning: control reaches end of non-void function [-wreturn-type] error?
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Lorraine O'Brien
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Asked: 2022-05-18T16:06:14+00:00 In:

Is there any solution for the warning: control reaches end of non-void function [-wreturn-type] error?

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I get the error: warning: control reaches end of non-void function [-wreturn-type] when I try to run the program below:

/*date difference calculator*/
 
 #include <stdio.h>
 
 int main()
 {
  int Date1 = 0, Date2 = 0, Dif, F, L, D1, D2, M1, M2, Y1, Y2;
  int x[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  int y[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
  char A1, A2, B1, B2;
 
 /*input first date*/
 
  fprintf (stderr , "Enter first date,in the form <day>/<month>/<year> or <day>-<month>-<year>.\nWhere <day>,<month> and <year> are integers:\n");
  (scanf("%i%c%i%c%i", &D1, &A1, &M1, &B1, &Y1));
 
 /*check first date*/
 
  if (!(Y1 % 4)) x[2]=29;
  while ((Y1 < 1 || (Y1 > 9999)) || (M1 < 1 || M1 > 12) || (D1 < 1 || D1 > x[M1]) || (A1 != B1) || ((A1 != '/') && (A1 != '-'))) 
  {
  fprintf (stderr, "Incorrect format, re-enter date:\n");
  scanf("%i%c%i%c%i", &D1, &A1, &M1, &B1, &Y1);
  if (!(Y1 % 4)) x[2]=29;
  }
 
 /*print first date*/
 
  fprintf (stderr, "First date = %i%c%i%c%i\n", D1 , A1 , M1 , B1 , Y1);
 
 /*input second date*/
 
  fprintf (stderr , "Enter second date,in the form <day>/<month>/<year> or <day>-<month>-<year>.\nWhere <day>,<month> and <year> are integers:\n");
  (scanf("%i%c%i%c%i", &D2, &A2, &M2, &B2, &Y2));
 
 /*check second date*/
 
  if (!(Y2 % 4)) y[2]=29;
  while ((Y2 < 1 || (Y2 > 9999)) || (M2 < 1 || M2 > 12) || (D2 < 1 || D2 > y[M2]) || (A2 != B2) || ((A2 != '/') && (A2 != '-'))) 
  {
  fprintf (stderr, "Incorrect format, re-enter date:\n");
  scanf("%i%c%i%c%i", &D2, &A2, &M2, &B2, &Y2);
  if (!(Y2 % 4)) y[2]=29;
  }
 
 /*print second date*/
 
  fprintf (stderr, "Second date = %i%c%i%c%i\n", D2 , A2 , M2 , B2 , Y2);
 
 /*convert first date into days*/
 
  for (F = 1; Y1 > F ; F++) 
  {
  if (F % 4 == 0) (Date1 = Date1 + 366);
  else (Date1 = Date1 + 365);
  }
  for (L = 1; M1 > L ; L++) 
  Date1 = Date1 + x[L];
  Date1 = Date1 + D1;
 
 /*convert second date into days*/
 
  for (F = 1; Y2 > F ; F++) 
  {
  if (F % 4 == 0) (Date2 = Date2 + 366);
  else (Date2 = Date2 + 365);
  }
  for (L = 1; M2 > L ; L++) 
  Date2 = Date2 + y[L];
  Date2 = Date2 + D2;
 
 /*standard output*/
 
  Dif = Date2 - Date1;
  printf("\n%i\n\n" , Dif);
 
 /*text output*/
 
  if (Date2 > Date1) 
  {Dif = Date2 - Date1;
  fprintf (stderr , "Indicating that the first date is %i days before second date.\n" , Dif);}
  if (Date1 > Date2) 
  {Dif = Date1 - Date2;
  fprintf (stderr , "Indicating that the second date is %i days before first date.\n" , Dif);} 
  if (Date1 == Date2) 
  fprintf (stderr , "Indicating that the first date is equal to second date.\n"); 
 }

The error appears the system notifies as follows:

date1.c: In function ‘main’:
 date1.c:70:1: warning: control reaches end of non-void function [-Wreturn-type]

I tried to solve it with another sample. I got the reference in the community forum, but it still returned an invalid result. If someone knows the solution, please give me the support. Thanks!

wreturn-type
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2 Answers

  1. Best Answer
    Expert

    The cause: This alert is comparable to the alert mentioned in “Return with no value”. It assumes a return with no return value if control exits a function without encountering a return. The function is supposed to return a value, but you’re not, so the warning occurs.

    Solution: At some point, you must return from the main function like:

      /* .... */
  if (Date1 == Date2)  
     fprintf (stderr , "Indicating that the first date is equal to second date.\n"); 

  return 0;
}

     

    • 0

  2. EXIT_SUCCESS can be used in place of return 0;. EXIT_SUCCESS can also be used instead of return 0;.

    • 10

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