How to print a given date in C - c

Question

I am very new to C programming. I was trying to use the scanf function to ask the user to enter a date and display it in the console. So wrote the following codes:
#include <stdio.h>
#include <stdlib.h>
int main() {
int date, month, year;
printf("Please enter the date in the form of dd/mm/yyyy: ");
scanf("%d/%d/%d", &date, &month, &year);
printf("the date you entered was: %d-%d-%d\n", date, month, year);
return 0;
}
But the output am getting is not in a proper format, for example, I type in "10-12-2016", but the result I get was "10-554502544-32766". Any idea guys? Thanks in advance.

Answer 1

In your scanf(), you have this format - %d/%d/%d but you are giving the input as 10-12-2016, so you are doing wrong!
Instead, you should give input as - 10/12/2016 and the %d/%d/%d part in scanf() will ignore the / part from the input.
I type in 10-12-2016, but the result I get was 10-554502544-32766. Any idea guys?
Yes, when you are giving 10-12-2016 as input, scanf() assigning only 10 to date variable but no value to the other variables. Since the other two variables month and year is uninitialized, you are getting garbage value (554502544 and 32766) when you print the value of variable month and year.
One way to check this: Just initialize the variable and then take input.
int date = 0, month = 0, year = 0;
scanf("%d/%d/%d", &date, &month, &year);
Now, if you give 10-12-2016 as input, you will get 10-0-0 as output. Hopefully you can understand what is actually happening!

Answer 2

scanf() is a fairly kludgy tool. It expects the format to be exactly as you specified and if it isn't you get weird behaviour.
You either need to enter the text exactly as specified (dd/mm/yy, not dd-mm-yy) or change how you go about things.
Consider having scanf() scan in a string that you then lex yourself to get the values you want - you can be much more tolerant of variances in the input that way, as well as be more proof against someone trying to break your program by deliberately giving it invalid input.

Answer 3

You need to check the return value from scanf - See the manual page
#include <stdio.h>
#include <stdlib.h>
int main() {
int date, month, year;
printf("Please enter the date in the form of dd/mm/yyyy: ");
if (scanf("%d/%d/%d", &date, &month, &year) == 3) {
printf("the date you entered was: %d-%d-%d\n", date, month, year);
} else {
printf("You have made an error\n");
}
return 0;
}

Answer 4

#include <stdio.h>
#include <stdlib.h>
int main() {
int date, month, year;
printf("Please enter the date in the form of dd press enter then enter mm then press enter then enter year then press enter.. ");
scanf("%d", &date);
scanf("%d", &month);
scanf("%d", &year);
printf("the date you entered was: %d/%d/%d\n", date, month, year);
return 0;
}