C program that displays shapes. Keep getting errors.

boilers969 · 10-11-2010, 01:22 AM

Code:

#include<stdio.h>

int main()
{
char shape=1;
int row;
 while(1)
        {


        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");      
        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;
}

Compiler messages:

shape.c: In function âmainâ:
shape.c:27: warning: ârowâ may be used uninitialized in this function
shape.c:35: warning: ârowâ may be used uninitialized in this function
shape.c:52: warning: ârowâ may be used uninitialized in this function

graemef · 10-11-2010, 01:25 AM

you have a break right at the end that will break out of the loop, remove that.

boilers969 · 10-11-2010, 01:30 AM

Here is a sample run:

Enter shape type (s/h/f):h
Enter shape length: 6

Enter shape type (s/h/f):Enter shape length:

Obviously its not showing the shape. And I need "Enter shape type (s/h/f):Enter shape length:" to be seperate lines.

Sergei Steshenko · 10-11-2010, 02:09 AM

Quote:

Originally Posted by boilers969

Code:

#include<stdio.h>

int main()
{
char shape=1;
int row;
 while(1)
        {


        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");      
        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;
}

Compiler messages:

shape.c: In function âmainâ:
shape.c:27: warning: ârowâ may be used uninitialized in this function
shape.c:35: warning: ârowâ may be used uninitialized in this function
shape.c:52: warning: ârowâ may be used uninitialized in this function

You seem to completely ignore what you've been told/asked.

This:

Code:

           int i,row;
           for(i=row;i>=1;i--)

piece of code is obviously wrong, you have already been told so, you have already been told about your lack of understanding of the very basic programming concept of variables initialization, yet you continue to write the same erroneous code.

Likewise,

Code:

                int i,j,k,row,m;
                m=row;

is obviously wrong.

Do you understand English ? What does C99 standard say on variables initialization ? What makes you think the variables are initialized ? Why do you even try to run the code if the compiler issues warnings ?

graemef · 10-11-2010, 02:19 AM

You have declared row right at the start of the main function you don't need to do it again (you have done so inside the case blocks). By declaring a variable with the same identifier in a block of code you hide the original local variable. In this case row had a value in it that the user had entered, but by redeclaring it you are hiding that value.

boilers969 · 10-11-2010, 03:24 PM

Its working just fine. The only thing I'm having problems with is terminating the program when the user enters a char other than s,h,f.

Code:

 if(shape!=s/h/f)
         return 0;

This is not working. It's giving me the following error. Which says they are undeclared.

Code:

shape.c: In function âmainâ:
shape.c:22: error: âsâ undeclared (first use in this function)
shape.c:22: error: (Each undeclared identifier is reported only once
shape.c:22: error: for each function it appears in.)
shape.c:22: error: âhâ undeclared (first use in this function)
shape.c:22: error: âfâ undeclared (first use in this function)

sag47 · 10-11-2010, 03:46 PM

That has already been answered here.

Before you take the time to ask any more questions please go through and read the responses we have already given you more carefully. Be sure to fully understand them.

And stop saying you understand when you don't understand.

You should look up on how to interpret compiler messages as well...

Quote:

shape.c:22: error: âsâ undeclared (first use in this function)

Means that there is a problem in the file shape.c on line 22. Look at line 22 of your code and figure out why it won't work.

boilers969 · 10-11-2010, 04:00 PM

I know how to read compiler messages. But in this earlier post you told me I had it right, and it doesn't work. I've tried several different things.

You had it before:

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");
      if(shape!=s/h/f)
         return 0;
   }
}

Nylex · 10-11-2010, 04:09 PM

Quote:

Originally Posted by boilers969

if(shape!=s/h/f)

What exactly are you trying to test here? Do you really want to divide s by h and then by f and compare that with shape?

boilers969 · 10-11-2010, 04:12 PM

My goal is to get the program to terminate if the user enters something other than "s,f,h". If they keep entering those then the program will keep running.

Nylex · 10-11-2010, 04:16 PM

How do you think your if statement is testing that? You've specified that the value of the variable shape be compared with the value of s/h/f, where s, h and f are all variables. You can do division with char variables, because they're treated as integers, I believe. However, I don't think that's what you intend to do..

boilers969 · 10-11-2010, 04:21 PM

I don't quite get your explanation. To me it seems like it should work because scanf stores either s,h,f into shape. And then if shape does not equal one of those it will terminate. That's how I read it.

Nylex · 10-11-2010, 04:26 PM

It seems that you're confused. You've written s/h/f and you're testing that this is not equal to the value stored in shape. Do you agree that / is for division? Do you also agree that you're referring to variables s, h and f? Since you haven't put those characters between single quotes, they refer to variables and not character literals 's', 'h' and 'f'. You haven't declared variables s, h and f, hence the compiler errors. Also, you probably want to look up the or operator in C..

boilers969 · 10-11-2010, 04:32 PM

They were telling me to use / earlier but yes that means division. The or operator is '||'.

This looks reasonable to me:

Code:

 if(shape!='s'||'h'||'f')
                return 0;

Nylex · 10-11-2010, 04:36 PM

Quote:

Originally Posted by boilers969

Code:

 if(shape!='s'||'h'||'f')
                return 0;

Looks fine to me.