Question

I am trying to sum values in a for loop with C. The initial value of variable x = 1 and I want to double it a set number of times and add the result. I have made the for loop, but my sum is always off by the initial value.

For example, if x = 1, the pattern should go:

1, 2, 4, 8, 16

…and the total should be 31. Unfortunately, total is off by one.

int x = 1;
int y = 10;
int total;

for(int i = 1; i < y; i++)
{   
   x *= 2;
   total += x;
}

printf("Total: %d\n", total);

This is off by one. How can I have the loop start with 1 instead of 2?

Answer 1

Switch the two statements in the body of the for loop. Also it is a good idea to initialize total to 0, in case you want to move all of this into a function.