I figured it out after trying some more and thought that might be of interest to others.

Code
function main() 
{
	int i;
	for (i = 0; i < 10; i++) {
		
		printf("i ist %i", i);
		if (i == 0) {
			string Name = file_next("CollectedHistory\\*.csv");
			printf("Der Filename lautet: %s \n", Name);
		} 
		else {
			string Name = file_next(0);
			printf("Der Filename lautet: %s \n", Name);
		}
		
	}
}