Thread: Problem with a sequence

Teh first term is 1, the second term is 2, and for all n>=3 the nth term is equal to term (n-1) plus term n/2, where n/2 is rounded down.

Program should prompt for n, and then display the nth term in the sequence. it can be assumed n is 50 or less. the program must contain a loop that keeps reading new values for n and then prints the nth term. The program show stop when n=0.

Code:

//tj wright 11.1
#include <stdio.h>

void main (void)
{
int q,m,n,x[50];

           for (m=1;m<=6;m++)

           {
           printf("enter n");
scanf ("%d", &n);
if (n==0) goto end;

x[1]=1;
x[2]=2;

for (q=3;q<=50;q++)
{
x[q]=x[q-1]=x[q/2];
}                     

printf("The number is %d\n",x[n]);

}
end:
}

When I run the program, it asks me to enter n, then I go to scan it in, and the program exits and points me to the x[2]=2; line. I am trying to trace the program and see where it is going wrong, but I cannot tell.

Can anyone tell me where I am going wrong?

"this steps off the end of the array"

What does that mean?

Obvious mistake:

Code:

  x[q]=x[q-1]=x[q/2];

I can't even get it to compile, it gives me:

error at line 23 (end label at end of compound statement
warning at line 3 (void main(void)) return type of 'main' is not 'int'

Last time i checked, "goto" was highly discouraged. Here, you can either use:
return; //supposing you don't fix the return type
return 0; //supposing you fix the return type to be int like it's supposed to be
exit(0); //works either way, but I'd generally encourage you to use "return 0;"

I could use break; instead of the goto, and it would work fine.

A better solution would be to change your main loop from a for loop to a while loop.

You could change this:

Code:

for (m=1;m<=6;m++)

to this:

Code:

while(n != 0)

Then you wouldent even need to use a goto or break to end the program.

Thank you all very much for your help and sharing your knowledge!

Originally Posted by itsme86

Code:

  int nums[10] = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };

Shouldn't that give an warning about an "excess elements in initializer" or somesuch? It does for me.