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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!
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:EXIT_SUCCESS
can be used in place ofreturn 0;
.EXIT_SUCCESS
can also be used instead ofreturn 0;
.