Added book examples

C4/reformatted_code.c

@@ -0,0 +1,19 @@
+#include <stdio.h>
+int main(void) 
+{
+	// Declare variables and give initial values 
+	int revenue = 80;
+	int cost = 50;
+	int roi;
+	
+	// Perform calculation
+	roi = (100 * (revenue - cost)) / cost;
+	
+	// Make decision based on value of roi
+	if (roi >= 0) 
+	{
+		printf ("%d\n", roi);
+	}
+
+	return 0;	// Exit indicating success
+}