1 files changed, 140 insertions, 0 deletions
diff --git a/pgm1/beetle.c b/pgm1/beetle.c
new file mode 100644
index 0000000..6b8a971
--- /dev/null
+++ b/pgm1/beetle.c
@@ -0,0 +1,140 @@
+#include<stdlib.h>
+#include<stdio.h>
+#include<math.h>
+#include<errno.h>
+
+/* 
+ * The purpose of this program is to simulate and record the average lifetimes
+ * of beetles on cardboard squares, suspended over vats of boiling oil. It takes
+ * in two parameters, both positive, long integers. The first integer refers
+ * to the length of one side of the cardboard square, in inches. The second
+ * refers to the number of beetles (number of times) with which to run this 
+ * simulation. 
+ *
+ * usage: ./beetle int int (./beetle square_size number_of_beetles)
+ */
+
+long double simulateLifetime(long int squareSize, long int beetleCount) {
+	/* 
+	 * simulateLifetime returns the collective lifetime of the beetles
+	 * suspended over the vat of oil. If this function fails to simulate any
+	 * beetles, it will return -1. 
+	 *
+	 * This simulation places a beetle at the center of a cardboard square. 
+	 * The cardboard square is represented by a coordinate grid, with the origin
+	 * being at the top-left corner, or the "home position". The 
+	 * beetle picks a random angle to move in, represented by random(),and moves 
+	 * forward 1 inch. This movement takes 1 second. The beetle waits 1 more
+	 * second before starting the whole process over again. Once the beetle's
+	 * coordinates move off the bounds of the coordinate grid, it "falls into
+	 * the vat" and the simulation continues with the next beetle, decreasing 
+	 * the count.
+	 * 
+	 * long int squareSize - represents the size of one side of the cardboard 
+	 * square.
+	 * 
+	 * long int beetleCount - represents the number of beetles to simulate, or 
+	 * rather, the number of times to run the simulation.
+	 */
+	
+	long double beetleX;
+	long double beetleY;
+	long double lifetime;
+	double angle;
+	long int count;
+	long int seconds;
+	
+	lifetime = -1;
+	count = beetleCount;
+	seconds = 0;
+		
+	while (count > 0) {
+		beetleX = squareSize / 2;
+		beetleY = squareSize / 2;
+		seconds = 0;
+		
+		while (beetleX >= 0 && beetleY >= 0 && beetleX <= squareSize 
+			&& beetleY <= squareSize) {
+			angle = random();
+			beetleX += cos(angle);
+			beetleY += sin(angle);
+			seconds++;
+			
+			if (beetleX >= 0 && beetleY >= 0 && beetleX <= squareSize 
+				&& beetleY <= squareSize) {
+				seconds++; // the beetle is resting but hasn't fallen off edge
+			}
+		}
+		
+		lifetime += seconds;		
+		count--;
+	}
+
+	return lifetime;
+}
+
+int main(int argc, char *argv[]) {
+	/* 
+	 * main sets up the beetle program. It reads the user's input and checks it
+	 * to make sure that it is valid. It converts the input to values that the
+	 * simulation function can use and then calls simulateLifetime(). main then
+	 * prints the output to the console.
+	 */
+	long double lifetime;
+	long int squareSize;
+	long int beetleCount;
+	char *squareTest;
+	char *countTest;
+	
+	// Check for improper number of arguments
+	if (argc != 3) {
+		fprintf(stderr, "beetle: usage: ./beetle int int\n");
+		exit(1);
+	} 
+	
+	errno = 0; // Reset error status
+	squareSize = strtol(argv[1], &squareTest, 10);
+	beetleCount = strtol(argv[2], &countTest, 10);
+	
+	// Check for invalid input 
+	if (squareTest == argv[1] || countTest == argv[2]) { 
+		fprintf(stderr, "beetle: usage: ./beetle int int\n");
+		exit(1);
+	}
+	
+	// Check for negative input
+	if (squareSize < 0 || beetleCount < 0) { 
+		fprintf(stderr, "beetle: error: input must be positive integers\n");
+		exit(1);
+	}
+	
+	// Check for overflow/underflow
+	if (errno == ERANGE) { 
+		fprintf(stderr, "beetle: error: int too large\n");
+        exit(1);
+	}
+	
+	// If no square to use for simulation then finish
+	if (squareSize == 0) {
+		fprintf(stderr, "No square given so lifetime is 0\n");
+		exit(0);
+	}
+	
+	// If no beetles given then finish
+	if (beetleCount == 0) {
+		fprintf(stderr, "No beetles given, so lifetime is 0\n");
+		exit(0);
+	}
+	
+	// Run simulation and check return value
+	if ((lifetime = simulateLifetime(squareSize, beetleCount)) == -1) { 
+		fprintf(stderr, "beetle: error: beetles have achieved immortality!\n");
+		exit(1);
+	}
+	
+	// Take the average of the beetles' lifetime and print the output. 
+	lifetime = lifetime / beetleCount; 
+	printf("%li by %li square, %li beetles, mean beetle lifetime is %.1Lf\n", 
+		squareSize, squareSize, beetleCount, lifetime);
+	exit(0);
+}