Thread: Why is fflush needed here?

OK, this is a part of a program that I wrote:

Code:

#include <stdio.h>
#include <string.h>

struct info {

	char firstname[20+1];
	char lastname[25+1];
	float score;
};

int main() {

	struct info student;

	do {

		printf("Type in the name: ");
		gets(student.firstname);

		if (strlen(student.firstname)==0) break;

		printf("Type in the last name: ");
		gets(student.lastname);

		printf("Type in the score: ");
		scanf("%f", &student.score);
		//fflush(stdin);	
		

	} while (1);

	return 0;
}

It didn't work this way (it allows me to enter data only once), so I put fflush(stdin) for no particular reason and now it works. Why is that?