Thread: stuck and getting tired of being so...

Hi there, I get stuck when I think I understand my classes every time and it never fails, I am getting REAL tired of it. Maybe someone can fill in my teachers BLANKS!

This code isn't working. All I get when I run it is 0's

Code:

#include <stdio.h>
#include <string.h>
/**************/
/*Brandi Savoy*/
/*asgn06.c    */
/*Monday Night*/
/**************/

#define PROGRAMMER "Brandi Savoy"
void name();
void eoj();
int readnum(int x);
int square(int x);
int cube(int x);
int add(int x, int y);
int subt(int x, int y);

void main()
{
 int num1, num2, sqrt1, sqrt2, cub1, cub2, tot, diff; 
 readnum(num1);
 readnum(num2);
 sqrt1 = square(num1);
 sqrt2 = square(num2);
 cub1 = cube(num1);
 cub2 = cube(num2);
 tot = add(num1, num2);
 diff = subt(num1, num2);

 name();
 printf("\nThe square of num1 is:\t\t\t\t\t %d\n\n", sqrt1);
 printf("The square of num2 is:\t\t\t\t\t %d\n\n", sqrt2);
 printf("The cube of num1 is:\t\t\t\t\t %d\n\n", cub1);
 printf("The cube of num2 is:\t\t\t\t\t %d\n\n", cub2);
 printf("The total of num1 and num2 is:\t\t\t\t %d\n\n", tot);
 printf("The difference between num1 and num2 is:\t\t %d\n\n", diff);
 printf("Press ENTER to continue");
 fflush(stdin);
 getchar();
}

int readnum(int x)
{
 int rn;
 name();
 printf("key in an integer:");
 fflush(stdin);
 scanf("%d", &rn);
 return rn;
}

int square(int x)
{
 return x * x; 
}

int cube(int x)
{
 return x * x * x;
}

int add(int x, int y)
{
 int ad = x + y; 
 return ad; 
}

int subt(int x, int y)
{
 int sb = x - y;
 return sb; 
}

void name()
{
 system("clear");
 printf("%s\n\n\n", PROGRAMMER);
}

void eoj()
{
 name();
 printf("EXECUTION COMPLETED... Press ENTER to contiune.\n");
 getchar();
}

Thanks in advance

your awesome! Thanks for clearing out my brain fart!!!

There is a lot of stuff in my class thats I just don't know why we learn that way. We lose marks if we don't code according to how we learned C. All this is good advice I will keep in mind, unfortunatly I have to keep the code (save for the ad function, return x + y;, I thought I got that one..) basically as it is.

We work in a unix system and I have had to put in fflush(stdin) a few times because it was giving me trouble without it. Dunno much about it in other systems but it seems to work in unix.

=)

By the way, in my humble opinion, this function is misleading, and could be modified in one of two ways:

Code:

int readnum(int x) //Why is it taking in the x value here? does nothing with it
{
   int rn;
   name();
   printf("key in an integer:");
   fflush(stdin);
   scanf("%d", &rn);
   return rn;
}

In this case, I did nothing more than replace the int x with void as int x was never used anywhere in the function to begin with.

Note, when calling this function, you should use it like this:
val1 = readnum();

Code:

int readnum(void) // Doesn't need to receive anything from main
{
   int rn;
   name();
   printf("key in an integer:");
   fflush(stdin);
   scanf("%d", &rn);
   return rn;
}

If you haven't learned pointers, ignore this.
It is also possible to return values to the main function by using pointers. This means that your function can return 1 or more values to different variables at the same time, yet lets you use the return to return a status report.

Code:

void readnum(int *x) //Modified to use pointers
{
   name();
   printf("key in an integer:");
   fflush(stdin);
   scanf("%d", x);
}

I don't know what system it is unless there is UNIX command you know that I can type in and it will tell me. it says on login "Machine Configuration: (IBM RS6000/S70 AIX 4.3.3) Does that mean something?

The only thing I am aware of fflush doign is it doesn't skip my getchars when I want the screen to hold before going onto the next screen, I had a few screens overpassed a fewtimse without fflush but other than that we are just told to put it in there before every scanf.

Originally Posted by Salem

> We work in a unix system and I have had to put in fflush(stdin)
Which one?
I don't think I've ever come across a unix system where this did anything other than either nothing or crash.
fflush() is for OUTPUT streams, and UPDATE streams following a write. stdin is an INPUT stream, and therefore can never be a valid stream for a fflush()

The need for attempting to flush the input stream pretty much goes away when you wean yourself off scanf(), and just stick to using fgets() as the sole method of primary input. Once the input is in a buffer, you can do whatever you want with it without worrying about messing up the input stream (as scanf does so readily).

LOL you know... your not the first person to say so... I've been reluctant to post for help because of this fact. I can't wait until Ican do my own C and get a proper understanding of it.

Originally Posted by Prelude

>We lose marks if we don't code according to how we learned C.
Your teacher is an idiot if he/she teaches bad C and then requires you to do so as well.

Originally Posted by escarrina

The only thing I am aware of fflush doign is it doesn't skip my getchars when I want the screen to hold before going onto the next screen, I had a few screens overpassed a fewtimse without fflush but other than that we are just told to put it in there before every scanf.

What happening here is the work of the scanf function...
In my experience with it(and alot of other more experienced programmers around here), scanf has a nasty tendency of leaving things in the input stream AKA stdin that can then screw up your other scanf()s, as well as getchar and getch.

The generally accepted way of cleaning the input buffer around here is actually mentioned in the faq.

essentially, replace the line
fflush(stdin);
with
char temp; // Remeber to put this where you initialize your variables...
while((temp = getchar()) != EOF ||temp != '\n');

this will clear out your input stream, and is as Prelude likes to say, "not undefined behavior"

Although I confess to using fflush(stdin); myslef sometimes when I'm lazy