Thread: Entry Level Help.

okay, think of this in two parts:

1) use a number [0-167] to find the day.

2) once you find the day, you have some remainder of an integer, use that to [0 - 23] to find the hour.

You need to use the logic AND operator && not the logical OR.
And the initial #define doesn't make any sense unless you want to set up a bit mask, which i guess you don't.
Perhaps you meant to use an enum instead.

Code:

enum day {Monday, Tuesday, Wednesday, Thirsday, Friday, Saturday, Sunday};

Also, consider the fact that days are multiples of 24, and a simple division will give you the day based on hours.

If we use the proposed enum to represent days, then the words Monday,Tuesday, etc will be automatically assigned by the C compiler to the constant numbers 0,1,..
The fact is that integer division in C, is done like it would cutoff decimals if decimals were there.
Eg: 23/5 = 4.6, but if 23 and 4 are of type int, then 23/5 == 4.
Consider the fact that every day has 24 hours, and a simple C integer division with 24 will give you the day of the week as a number, starting from 0.

The definition of enum is that the names within it are mapped to numbers, constant numbers for the program.

Code:

enum fruits {Apples, Bananas, Oranges, Lemons};

The type of Apples, Bananas, Oranges, Lemons is int.
Their values are 0,1,2,3
It is just the C way of not having to write 0,1,2,3 where you would want to refer to a specific 'fruit'.
You can use enum fruits as a type for a variable, it evaluates to int.
So:

Code:

    enum fruits z;
    int k;

Is the C way of telling the same thing. enum is there to provide a short and easy way to make tag markers for simple sets with elements that are unique and different and are represented as a number.
Do you find it clearer now?

1. Try moving the enum type declaration outside main.
2. If you insist to find the day using if, then read aloud what you are testing for in every case, and look again at my first post where i mention something about using the wrong logical operator.
3. You find the day in the variable named 'day', but print the variable named 's'.

I understand my mistake with logical operators. Thank you. Now I get a value of 0,1,2,3,4,5,6when I run the program. It is printing the enums and not the days of the week.

Code:

     7  #include <stdio.h>
     8
     9
    10  enum day {Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday};
    11
    12
    13  int main(void)
    14
    15  {
    16
    17  int hour, day;
    18
    19  printf("Enter hours: ");
    20  scanf("&#37;d", &hour);
    21
    22  if (hour < 24)
    23  day = Monday;
    24  else if (hour > 23 && hour < 48)
    25  day = Tuesday;
    26  else if (hour > 47 && hour < 72)
    27  day = Wednesday;
    28  else if (hour > 71 && hour < 96)
    29  day = Thursday;
    30  else if (hour > 95 && hour < 120)
    31  day = Friday;
    32  else if (hour > 119 && hour < 144)
    33  day = Saturday;
    34  else
    35  day = Sunday;
    36
    37  printf("Result: %d\n", day);
    38  printf("PROGRAM ENDS\n");

Good to see you understand the errors, and more so that you learn from them.
As i told you the program would print numbers. We use enum, so that we can write programs that are more descriptive of their operation.

Code:

    ....
    26  else if (hour > 47 && hour < 72)
    27  day = 2;

Which is more understandable, your version or the one i wrote here?
If you need to print the days of the week in human readable format you will need to tell your program, to map the numbers to text. We usually use an array of constant string to do that.
For example.
I would write:

Code:

enum fruit {Apple, Orange, Banana, Lemon};
char fruitName[4][7] = {"Apple", "Orange", "Banana", "Lemon"};

int main()
{
    int iLike;

    printf("What fruit do you like?\n");
    printf("1. Apple\n");
    printf("2. Orange\n");
    printf("3. Banana!\n");
    printf("4. Lemon?\n");
    scanf("%d", &iLike);
    iLike++;   /* the enum constants start from 0 in this example */
    if(iLike==Apple || iLike==Orange || iLike==Banana || iLike==Lemon)
        printf("So you really like [%s]? Me too!\n", fruitName[iLike]);
    else
        printf("Hmmm... raw meat sound good to you huh?\n");
    return 0;
}

Notice the use of the human readable names to verify that the user actually likes a fruit.
Doesn't it make it much easier to read the purpose of the program?

Few errors/fixes in the fruit example

Code:

enum fruit {Apple = 0, Orange, Banana, Lemon, Num_Fruits};
char fruitName[4][7] = {"Apple", "Orange", "Banana", "Lemon"};

int main()
{
    int iLike;

    printf("What fruit do you like?\n");
    printf("1. Apple\n");
    printf("2. Orange\n");
    printf("3. Banana!\n");
    printf("4. Lemon?\n");
    scanf("%d", &iLike);
    iLike--;   /* the enum constants start from 0 in this example */
    if(iLike < Num_Fruits)
        printf("So you really like [%s]? Me too!\n", fruitName[iLike]);
    else
        printf("Hmmm... raw meat sound good to you huh?\n");
    return 0;
}

johnyc@pazuzu:~/Projects/test$ cat enum.c

Code:

#include <stdio.h>

enum {A,B,C,D};

int main()
{
        printf("A: &#37;d, B: %d, C: %d, D: %d\n",A,B,C,D);
        return 0;
}

johnyc@pazuzu:~/Projects/test$ gcc -o enum enum.c
johnyc@pazuzu:~/Projects/test$ gcc -Wall -ansi -pedantic -o enum enum.c
johnyc@pazuzu:~/Projects/test$ ./enum
A: 0, B: 1, C: 2, D: 3
johnyc@pazuzu:~/Projects/test$

I believe enumerated constants start at 0 by default.

As for the test, it was purposefully written such that it demonstrates the readability of enum constants versus "magic" numbers.