C program that displays shapes. Keep getting errors.

boilers969 · 10-11-2010, 12:27 AM

Yes I'm understanding that. But since I can't have any global variables, where can I declare char shape??

Nylex · 10-11-2010, 12:28 AM

Wow, this thread has certainly grown overnight..

Quote:

Originally Posted by sag47

Code:

char shape=1;
shape='c';
switch(shape)
{
    case 'a':
        return 0;
    case 'b':
        return 0;
    default:
        return 1;
}

You can make that even more compact with

Code:

case 'a':
case 'b':
  return 0;

graemef · 10-11-2010, 12:34 AM

Quote:

Originally Posted by boilers969

Yes I'm understanding that. But since I can't have any global variables, where can I declare char shape??

shape will be declared within the main function. It will then be available to the switch statement which is in the main. Which will be within your while loop (as you asked about that earlier).

Now might be a good time to post your code as it stands so that we can have a good look at it and help you iron out any problems. Also include any compile errors or warnings that you may have.

boilers969 · 10-11-2010, 12:42 AM

So are you saying the while loop will contain the switch statment?

Code:

#include<stdio.h>

int main()
{
 while(1)
        {
        char shape=1;                                                
        int row;                                                     
        printf("Enter shape type (s/h/f):");                        
        scanf("%c",&shape);                                          
        printf("Enter shape length: ");                              
        scanf("%d",&row);                                            
        if(row<=0)                                                   
        printf("Shape length cannot be negative. Try again\n");      
        }
char shape=1;
shape='s','h','f';
   switch(shape)
   {
        case s:
{
           int i,row;
           for(i=row;i>=1;i--)
                printf("*\n");
           break;
           }

        case h:
{
           int i,j,k,row,m;
           m=row;
           for(i=1 ; i<=m; i++)
           {
                for (j=1 ; j>=row; j--)
                   printf(" ");
{
                   for(k=1; k<=i; k=k+1)
                        printf("*");

                  printf("\n");
           }
        }
        break;
        }

        case f:
{
                int i,j,k,row,m;
                m=row;
                for(i=0;i<m;i++)
                {
                   printf("\n");
                   for(k=0;k<row;k++)
                        printf(" ");
                   for(j=0;j<=i;j++)
                        printf(" *");
                   row--;
                }
        }
}
printf("\n");
break;
}
}
}
return 0;
}

Errors:

shape.c: In function âmainâ:
shape.c:25: error: âsâ undeclared (first use in this function)
shape.c:25: error: (Each undeclared identifier is reported only once
shape.c:25: error: for each function it appears in.)
shape.c:33: error: âhâ undeclared (first use in this function)
shape.c:50: error: âfâ undeclared (first use in this function)
shape.c:66: error: break statement not within loop or switch
shape.c: At top level:
shape.c:68: error: expected identifier or â(â before â}â token
shape.c:69: error: expected identifier or â(â before â}â token
shape.c:70: error: expected identifier or â(â before âreturnâ
shape.c:71: error: expected identifier or â(â before â}â token

sag47 · 10-11-2010, 12:46 AM

Yes. while(1) { } is an infinite loop. It will never get to char shape=1. Anything that you do with your code MUST be within the while loop if it is while(1).

So your code should look like

Code:

int main()
{
  while(1)
  {
    ...program about everything;
  }
}

There shouldn't be anything outside of while(1) below it. You can set variables and other conditions to be used within the while(1) above it however.

Also in order for your program to be successful in any way it has to exit some how. So somewhere in the while(1) you need to have a return statement.

boilers969 · 10-11-2010, 12:49 AM

Right!

Code:

#include<stdio.h>

int main()
{
 while(1)
        {
        char shape=1;                                                
        int row;                                                     
        printf("Enter shape type (s/h/f):");                        
        scanf("%c",&shape);                                          
        printf("Enter shape length: ");                              
        scanf("%d",&row);                                            
        if(row<=0)                                                   
        printf("Shape length cannot be negative. Try again\n");      

        char shape=1;
        shape='s','h','f';
   switch(shape)
   {
        case s:
{
           int i,row;
           for(i=row;i>=1;i--)
                printf("*\n");
           break;
           }

        case h:
{
           int i,j,k,row,m;
           m=row;
           for(i=1 ; i<=m; i++)
           {
                for (j=1 ; j>=row; j--)
                   printf(" ");
{
                   for(k=1; k<=i; k=k+1)
                        printf("*");

                  printf("\n");
           }
        }
        break;
        }

        case f:
{
                int i,j,k,row,m;
                m=row;
                for(i=0;i<m;i++)
                {
                   printf("\n");
                   for(k=0;k<row;k++)
                        printf(" ");
                   for(j=0;j<=i;j++)
                        printf(" *");
                   row--;
                }
        }
}
printf("\n");
break;
}
}
}
return 0;
}

How does that look? I might be off by a bracket somewhere.

graemef · 10-11-2010, 12:50 AM

Yes include the switch in the while loop

Code:

int main()
{
   while(1)
   {
      /* Code to get the value of shape */
      switch (shape)
      {
         case 's':
            /* code to handle the shape 's' */
            break
         /* the remaining case statements */
      } /* end of switch */
   } /* end of while loop forever */

} /* end of main function */

Note that the value held by shape be it a s h or f must be in single quotes 's', 'h' or 'f'

You don'd need to declare the variable a second time (I guess that you put it there because the compiler complained that it doesn't know about a variable called shape. This is because you declared it in the loop.)

graemef · 10-11-2010, 12:53 AM

Just to clarify what I was saying. From your code in post #66

Code:

        if(row<=0)                                                   
        printf("Shape length cannot be negative. Try again\n");      

        char shape=1;
        shape='s','h','f';

The red lines are not needed.

sag47 · 10-11-2010, 12:55 AM

While you're at it, since you're scanning keyboard input by passing a reference it is better to declare shape outside of your while loop as you only need declare it once.

Code:

int main()
{
   char shape=1;
   /* declare any other variables which have references within the while loop */
   while(1)
   {
      /* Code to get the value of shape */
      switch (shape)
      {
         case 's':
            /* code to handle the shape 's' */
            break
         /* the remaining case statements */
      } /* end of switch */
   } /* end of while loop forever */

} /* end of main function */

boilers969 · 10-11-2010, 12:56 AM

So is this command correct?

Code:

shape='s','h','f';

boilers969 · 10-11-2010, 12:57 AM

Wait...I don't even need that line?

boilers969 · 10-11-2010, 01:06 AM

Do I need to declare the char s,h, and f anywhere? Because I'm getting the error that they are undeclared. And I understand why.

graemef · 10-11-2010, 01:12 AM

When you refer to s you are referring to the character value s. Not a variable that could be any value. but the specific value s. These are called character literals, and in C you enclose them in single quotes. Hence you would have case 's': not case s: Okay.

boilers969 · 10-11-2010, 01:15 AM

Ok got it! I got it to compile. But its not working the way it should. It terminates after the first round. Do you want me to post what I got?

graemef · 10-11-2010, 01:19 AM

Post your code along with any compiler messages.