Think like a programmer: Simplifying redundacy in C (Beginner)

[Riddle]

I had to modify the variables pretty heavily to get it trk in my old ass compiler from the 90s.

But, removed more redundancy by combing IF statements. Shortened by lessening the number of variables.

Very nice! Thanks for the contribution! I had completely forgotten about SWITCH Statements... but then again, I just started learning C and I haven't experimented with them.

It could be simplified a little bit more utilizing one of your methods by simplifying another one of the If Statements:

#include <stdio.h>
#include <conio.h>
#include <math.h>
#define PI 3.14159
int main()
{
	char buffer[32];
	char* info[3] = {"area", "diameter", "radus"};
	float area = 0, diameter = 0, radius = 0, value = 0;
	int selection = 0, valid = 0;
	clrscr();
	printf("Calculate the Area, Radius, or Diameter of a circle\nWhat is the information you have?\n1. Area\n2. Radius\n3. Diameter\nEnter a number 1-3: ");
	if (fgets(buffer, sizeof buffer, stdin) != NULL && sscanf(buffer, "%d", &selection) && selection > 0 && selection < 4)
	{
		printf("What is the value for the %s? ", info[selection - 1]);
		if (fgets(buffer, sizeof buffer, stdin) != NULL && sscanf(buffer, "%f", &value) == 1)
		{
			switch (selection)
			{
				case 1 :
					area = value;
					radius = sqrt(area / PI);
					diameter = 2 * radius;
					break;
				case 2 :
					radius = value;
					area = PI * pow(radius, 2);
					diameter = 2 * radius;
					break;
				default :
					diameter = value;
					radius = diameter / 2;
					area = PI * pow(radius, 2);
				}
				printf("Area = %.2f\nRadius = %.2f\nDiameter = %.2f\n", area, radius, diameter);
				valid = 1;
			}
		}
		else
			printf("Invalid number!\n");
	}
	else
		printf("No such option!");
	getch();
	if (!valid)
		main();
	return 0;
}

I didn't test this, but it should work. I just took out like 3 lines only though. >_<