Thread: Looping and generally awkward scenarios

Hey guys, I have an exam in C programming I'm a little stuck on loops...

I have to make a program that multiplies the loop variable by 2 then takes away 1... easy, that was a for loop no problem

for (x=3; x<=65; x=x*2-1)

that should print out 3 5 9 17 33 65

however, my lecturer has given the task for it to reverse, but not to display the number 17 on the way back down using an if statement...
however, this time it must be a do while loop... This is what I have so far.

Code:

#include <stdio.h>
#include <stdlib.h>


int main()
{
    int x = 129;


    do
    {
        x = (x/2) + 1;
        
        printf("%d \n", x);


    }
    while (x >= 4);


    return 0;
}

I'm not sure what you want to know. Put an if statement inside your loop to determine whether or not you actually do the print statement, and you appear to be done.

I should of been more specific, how do I tell the program not to display the number 17?

I did try if(x=17){printf(" ");
however that just made the program continually loop 17, when I changed = to == it just put a space in front of the 17. I've only started programming a month ago.

Maybe you should have a look at the continue statement...

So you only want to print when x isn't 17....................

No I want it to print 65, 33, 9, 5, 3... Heres the scenario

· Demonstrates a ‘for’ loop that produces the output: 3, 5, 9, 17, 33, 65. (Hint: the loop variable value is first doubled, then reduced by 1)
· Demonstrates a ‘do’ – ‘while’ loop that does exactly the same, just the other way round (Hint: first add 1 to the loop variable, then divide by 2). However, the 17 must not be printed out, i.e. the output is: 65, 33, 9, 5, 3.

I've managed to work it out now

Code:

#include <stdio.h>
#include <stdlib.h>


int main()
{
    int x = 129;


    do
    {
        x = (x/2) + 1;
        //if statement to find the number you want to play with
        if(x == 17){
            //skips the number you've chosen and continues to run the loop.WHITELOOPSppt page 32    
            continue;
        }


        printf("%d \n", x);


    }
    while (x >= 4);


    return 0;
}

suddenly clicked >.<