Thread: Can someone help me with my next day program, please!

Hello there,
i am trying to rewrite this program taht should take 2 integers- say 17 and 5 which represent 17 May and print out 18 May which is the next day.
I could use any constuctive comments and/or help that will enable me to get my program up and running quickly.
One of my questions is do i need to write another enum and switch functions for the days eg; mon - sat or can i already somehow shorten and manipulate my code? I am trying for something short and sweet, folks.

Code:

#include<stdio.h>

enum month {jan,feb,mar,apr,may,jun,jul,aug,sep,oct,nov,dec}; /*This allows yoou to name a finite set and to declare identifiers*/
typedef enum month	month;

month previous_month(month M)  /*this is a function definition*/
{
	switch (M) /* like an if-else statement, if this month is true goto the M=month you chose*/
		{
	case  jan:
		M=dec;break;
	case  feb:
		M=jan;break;
	case  mar:
		M=feb;break;
	case apr:
		M=mar;break;
	case may:
		M=apr;break;
	case jun:
		M=may;break;
	case jul:
		M=jun;break;
	case aug:
		M=jul;break;
	case sep:
		M=aug;break;
	case oct:
		M=sep;break;
	case nov:
		M=oct;break;
	case dec:
		M=nov;break;
	} 
	return M;
}

void print_month (month M)  /*this is a function definition*/
{
	switch (M)  /* like an if-else statement, if this month is true goto the M=month you chose*/
	{
	case jan:
		printf("January");break;
	case feb:
		printf("February");break;
	case mar:
		printf("March");break;
	case apr:
		printf("April");break;
	case may:
		printf("May");break;
	case jun:
		printf("June");break;
	case jul:
		printf("July");break;
	case aug:
		printf("August");break;
	case sep:
		printf("September");break;
	case oct:
		printf("October");break;
	case nov:
		printf("November");break;
	case dec:
		printf("December");break;
	} 
}

int main()
{
	month M, N, sat;
	printf("Table of months and thier predecessors\n");
	scanf("%d%d", &M, &N);
	printf("\n %16s%16s\n", "Month", "Day");
	for (M = jan; M <= sat; ((int)M + 1)) 
	{
		printf("");
		print_month(M);  /*fucntion call to print month*/
		printf("");
		print_month(previous_month(M));  /*fucntion call to print previous month*/
		putchar('\n');
		return;
	}
}

>int main()
should really be
>int main(void)

>month M, N, sat;
>for (M = jan; M <= sat; ((int)M + 1))
sat is not assigned a value before you use it in the test. Because of this, the loop didn't run on my system.

>printf("");
What are you trying to do here? You're not printing anything.

>previous_month()
This function could simply decrement the month variable, ensure it's not negative and return. It doesn't really need to switch statement. This will give you the same end result in a lot less code.

>print_month()
Again, you could make some changes to loose the switch statement. Namely, store the month strings in an array, and use M as the index. But I expect that's a lesson for another day.