Problem with structured lists from text

[Sertaba]

New to this C stuff, and was going through Kochan's book Programming in C and got to chapter 9 structured lists.

There's this problem that requires you to set a Variable N that calculates days.

N = 1461 x f(year, month) / 4 + 153 x g(month) / 5 + day

where
f(year, month) = year-1 (if month <=2)
=year (otherwise)

g(month) = month+13 (if month <=2)
= month+1 (otherwise)

struct date { 


int month;
int day; 
int year; 


};


struct date daycalc (struct date entry){
struct date count;




if(entry.month <=2){
entry.year-1;
entry.month + 13;
}


else{
entry.year ;
entry.month+1;
}


return entry;


}


void main (){


struct date daycalc (struct date entry); 
struct date firstDay, secondDay, T1;
int N1;


printf("Please enter mm/dd/yyyy: ");
scanf("%i%i%i", &firstDay.month, &firstDay.day, &firstDay.year);
T1=daycalc(firstDay);




;N1=( 1461 * T1.year ) / 4 + ( 153 * T1.month ) / 5 + T1.day;

}

I was having issues getting the right values for N so I tried to see what
T1.year gives me when I type in firstDay.month=02, firstDay.day=08 and firstDay.year=1999, and I got 8. According to book I should be getting 1998.

What did I do wrong?

[AndiPersti]

For a start you could look at the compiler warnings:

e$ make foo
cc -ggdb3 -Wall -Wextra    foo.c   -o foo
foo.c: In function ‘daycalc’:
foo.c:19:1: warning: statement with no effect [-Wunused-value]
foo.c:20:1: warning: statement with no effect [-Wunused-value]
foo.c:25:1: warning: statement with no effect [-Wunused-value]
foo.c:26:1: warning: statement with no effect [-Wunused-value]
foo.c:13:13: warning: unused variable ‘count’ [-Wunused-variable]
foo.c: At top level:
foo.c:36:6: warning: return type of ‘main’ is not ‘int’ [-Wmain]
foo.c: In function ‘main’:
foo.c:44:1: warning: implicit declaration of function ‘printf’ [-Wimplicit-function-declaration]
foo.c:44:1: warning: incompatible implicit declaration of built-in function ‘printf’ [enabled by default]
foo.c:45:1: warning: implicit declaration of function ‘scanf’ [-Wimplicit-function-declaration]
foo.c:45:1: warning: incompatible implicit declaration of built-in function ‘scanf’ [enabled by default]
foo.c:41:5: warning: variable ‘N1’ set but not used [-Wunused-but-set-variable]
foo.c:40:23: warning: unused variable ‘secondDay’ [-Wunused-variable]

Bye, Andreas

[Sertaba]

For a start you could look at the compiler warnings:

e$ make foo
cc -ggdb3 -Wall -Wextra    foo.c   -o foo
foo.c: In function ‘daycalc’:
foo.c:19:1: warning: statement with no effect [-Wunused-value]
foo.c:20:1: warning: statement with no effect [-Wunused-value]
foo.c:25:1: warning: statement with no effect [-Wunused-value]
foo.c:26:1: warning: statement with no effect [-Wunused-value]
foo.c:13:13: warning: unused variable ‘count’ [-Wunused-variable]
foo.c: At top level:
foo.c:36:6: warning: return type of ‘main’ is not ‘int’ [-Wmain]
foo.c: In function ‘main’:
foo.c:44:1: warning: implicit declaration of function ‘printf’ [-Wimplicit-function-declaration]
foo.c:44:1: warning: incompatible implicit declaration of built-in function ‘printf’ [enabled by default]
foo.c:45:1: warning: implicit declaration of function ‘scanf’ [-Wimplicit-function-declaration]
foo.c:45:1: warning: incompatible implicit declaration of built-in function ‘scanf’ [enabled by default]
foo.c:41:5: warning: variable ‘N1’ set but not used [-Wunused-but-set-variable]
foo.c:40:23: warning: unused variable ‘secondDay’ [-Wunused-variable]

Bye, Andreas

I accidentally posted it with a typo. Here's the one that should work. Thanks.

#include <stdio.h>


struct date {


int month;
int day;
int year; 


};


struct date daycalc (struct date entry){






if(entry.month <=2){
entry.year-1;
entry.month + 13;
}


else{
entry.year ;
entry.month+1;
}


return entry;


}


void main (){


struct date daycalc (struct date entry);
struct date firstDay, secondDay, T1;
int N1;


printf("Please enter mm/dd/yyyy: ");
scanf("%i%i%i", &firstDay.month, &firstDay.day, &firstDay.year);
T1=daycalc(firstDay);




N1=( 1461 * T1.year ) / 4 + ( 153 * T1.month ) / 5 + T1.day;


//printf("%i", N1);
printf("%i", T1.year);




}

Nevermind I see what you mean. My compiler doesn't have any of those warnings.

Ok, I see how you got those warnings. Aw this makes sense. Anyway thanks once again.