#include <stdio.h>

main()
{
	float number1;
	char operation;
	float number2;
	float answer;

	printf("enter a number, then press enter: ");
	scanf("%f", &number1);
	printf("\nenter an operation, be it plus (+), minus (-), times (*), or divided by (/), then press enter: ");
	scanf("%c", operation);
	printf("\nenter another number, then press enter: ");
	scanf("%f", &number2);
	if (operation == '+')
		answer = number1 + number2;
	if (operation == '-')
		answer = number1 - number2;
	if (operation == '*')
		answer = number1 * number2;
	if (operation == '/')
		answer = number1 / number2;
	printf("\nenter an operation, be it plus (+), minus (-), times (*), or divided by (/), then press enter.  If you're done with your calculation then enter \"end\" (no quotes) and press enter: ");
	scanf ("%c", operation);

	while (operation != 'end') {
		if (operation == '+') {
			printf("\nenter another number, then press enter: ");
			scanf("%f", &number2);
			answer = answer + number2;
			printf("\nenter an operation, be it plus (+), minus (-), times (*), or divided by (/), then press enter.  If you're done with your calculation then enter \"end\" (no quotes) and press enter: ");
			scanf("%c", operation);
		}
		else if (operation == '-') {
			printf("\nenter another number, then press enter: ");
			scanf("%f", &number2);
			answer = answer - number2;
			printf("\nenter an operation, be it plus (+), minus (-), times (*), or divided by (/), then press enter.  If you're done with your calculation then enter \"end\" (no quotes) and press enter: ");
			scanf("%c", operation);
		}
		else if (operation == '*') {
			printf("\nenter another number, then press enter: ");
			scanf("%f", &number2);
			answer = answer * number2;
			printf("\nenter an operation, be it plus (+), minus (-), times (*), or divided by (/), then press enter.  If you're done with your calculation then enter \"end\" (no quotes) and press enter: ");
			scanf("%c", operation);
		}
		else if (operation == '/') {
			printf("\nenter another number, then press enter: ");
			scanf("%f", &number2);
			answer = answer / number2;
			printf("\nenter an operation, be it plus (+), minus (-), times (*), or divided by (/), then press enter.  If you're done with your calculation then enter \"end\" (no quotes) and press enter: ");
			scanf("%c", operation);
		}
		else if (operation != '+' | operation != '-' | operation != '*' | operation != '/') {
			printf("\nthat's not a valid operation!  Enter a correct operation: plus (+), minus (-), times (*), or divided by (/), then press enter.  If you're done with your calculation then enter \"end\" (no quotes) and press enter: ");
			scanf("%c", operation);
		}
		else {
			printf("\nthat's not a valid operation!  Enter a correct operation: plus (+), minus (-), times (*), or divided by (/), then press enter.  If you're done with your calculation then enter \"end\" (no quotes) and press enter: ");
			scanf("%c", operation);
		}
	}
	printf("\nThe answer to your operation is %f.\n", answer);
}