I thought it meant that I hadn't declared a variable but I have.

Code:
int DoubleNumbers(int seq[], int *digitNum)
{
	int i, j;

	for (i = 0; i = 9; i++)
		for (j = i + 1; j = 9; j++)
			if (seq[i] == seq[j]){
				*digitNum = j;
				return 1;
			}
	return 0;
}
An error message comes up and says that both i and j are "undeclared...