Loop back after wrong input, problem with fgetc(stdin) and loop - c

Question

So i have this simple code that i've found here. I want to make it work in a loop. I've tried couple of times with diffrent methods but output is bad. Working in Ubuntu Visual Studio
EDIT I've added if(y>=2015 && y<=3000) and it is working properly?
EDIT 2 I've modified my code and followed #Sergey advice... It is still not working properly...
I've tried to add "Check return value of scanf" but it is also not working.
if ((scanf("%u", &d) == 1) && (scanf("%u", &m) == 1) && (scanf("%u", &y) == 1))
while (fdateCheck());
else
//...EOF or conversion failure...
while (fdateCheck());
or
while ((rc = scanf("%u.%u.%u", &d, &m, &y)) != EOF)
{
if (rc != 3)
//...oops data problems...
else
//...all OK...
}
Need advice about checking return of scanfs
int fdateCheck();
unsigned int d,m,y;
unsigned int daysinmonth[12]={31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int rc;
int legit = 0;
int main()
{
printf("Enter the date\n");
scanf("%u.%u.%u",&d,&m,&y);
while (fdateCheck());
}
int fdateCheck()
{
if (y % 400 == 0 || (y % 100 != 0 && y % 4 == 0))
{
daysinmonth[1]=29;
}
else if (y >= 2015 && y <= 3000)
{
if (m < 13)
{
if (d <= daysinmonth[m-1])
legit = 1;
}
if (legit == 1)
{
system("clear");
printf("It is a legitimate date!\n");
return 0;
}
}
else
system("clear");
int ch = fgetc(stdin);
if (ch == '\n')
{
system("clear");
printf("It's not a legitimate date!\n");
printf("\nRetry: ");
return 1;
}
fflush(stdin);
}

Answer 1

If you have an appropriate code in the function void main() and need to repeat it in a cycle as you describe you can do the following:
rename original void main() to int one_step()
put return 0; after printf("It is a legitimate date!\n");
put return 1; after printf("It's not a legitimate date!\n");
create the new void main() function as:
void main() {
while(one_step());
}
You do not need break; and return main();. You may need some enhancements as described in the comments above. Good luck in coding!
UPDATE #1
I meant such an improvement of your code:
#include <stdio.h>
#include <stdlib.h>
int fdateCheck();
int main()
{
while (fdateCheck());
}
int fdateCheck()
{
int res;
int legit = 0;
unsigned int d,m,y;
unsigned int daysinmonth[12]={31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
// get input block
printf("Enter the date\n"); // prompt for data
res = scanf("%u.%u.%u",&d,&m,&y); // get input data
if (res == EOF) { // check if no more input
printf("Input error\n");
exit(1);
}
// check if input data is valid
if (res != 3) { // check if 3 numbers scanned
system("clear");
printf("It is not a date\n");
fflush(stdin);
return 1;
}
// make leap year correction
if (y % 400 == 0 || (y % 100 != 0 && y % 4 == 0)) {
daysinmonth[1]=29; // leap year correction
}
// check if year, month and day is valid
if (y >= 2015 && y <= 3000) { // check if year in this range
if (0 < m && m < 13) { // check if month in this range
if (0 < d && d <= daysinmonth[m-1]) // check if day in this range
legit = 1;
}
}
// print a message and finish the iteration
if (legit == 1) {
printf("It is a legitimate date!\n");
return 0;
}
else {
system("clear");
printf("It's not a legitimate date!\n");
printf("Please retry.\n");
fflush(stdin);
return 1;
}
}
I also moved all variables inside the function. This will restore values of legit and daysinmonth[1] before each iteration.
UPDATE #2
My next proposal:
#include <stdio.h>
#include <stdlib.h>
int fdateCheck();
int main()
{
while (fdateCheck());
}
int fdateCheck()
{
int res;
int legit = 0;
unsigned int d,m,y;
unsigned int daysinmonth[12]={31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
// get input block
printf("Enter the date\n"); // prompt for data
res = scanf("%u.%u.%u",&d,&m,&y); // get input data
if (res == EOF) { // check if no more input
printf("Input error\n");
exit(1);
}
// check if input data is valid
if (res != 3) { // check if 3 numbers scanned
fgetc(stdin); // remove a barrier
system("clear");
printf("It is not a date\n");
fflush(stdin);
return 1;
}
// make leap year correction
if (y % 400 == 0 || (y % 100 != 0 && y % 4 == 0)) {
daysinmonth[1]=29; // leap year correction
}
// check if year, month and day is valid
if (y >= 2015 && y <= 3000) { // check if year in this range
if (0 < m && m < 13) { // check if month in this range
if (0 < d && d <= daysinmonth[m-1]) // check if day in this range
legit = 1;
}
}
// print a message and finish the iteration
if (legit == 1) {
printf("It is a legitimate date!\n");
return 0;
}
else {
system("clear");
printf("It's not a legitimate date!\n");
printf("Please retry.\n");
fflush(stdin);
return 1;
}
}