move exercises and lectures into subfolders

Lectures/LC20/AreaFunc.c

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+#include <stdio.h>
+#include <math.h>
+
+
+float CalculateAreaOfCircle ( float radius )
+{
+	float area;
+	area = M_PI * radius * radius ;
+	return (area) ;
+}
+
+float CalculateSurfaceAreaOfCylinder ( float radius, float length )
+{
+	float area;
+	area = 2.0 * ( M_PI * radius * radius ) + ( M_PI * 2.0 * radius * length );       // two ends + side
+	return (area) ;
+}

Lectures/LC20/AreaFunc.h

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+float CalculateAreaOfCircle ( float radius );
+float CalculateSurfaceAreaOfCylinder ( float radius, float length );

Lectures/LC20/Main.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+#include"AreaFunc.h"
+
+/* Show use of function  */
+int main (void)
+{
+	// Declare variables - no need to initialise as values will be read in / calculated
+	float rad, len, Area, SurfaceArea;
+
+	// Prompt for and obtain value
+	printf ("Please enter the raduis of the circle: ");
+	scanf ("%f", &rad);
+
+    printf ("Please enter the length of the cylinder: ");
+	scanf ("%f", &len);
+
+	// Calculate the area of the circle
+	Area = CalculateAreaOfCircle(rad);
+
+	// And display the answer on the screen
+	printf ("The area of a circle of radius %f is %f\n", rad, Area );
+
+	// Calculate the surface area of the cylinder
+	SurfaceArea = CalculateSurfaceAreaOfCylinder(rad, len);
+
+	// And display the answer on the screen
+	printf ("The surface area of a cylinder of radius %f and length %f is %f\n", rad, len, SurfaceArea );
+
+	// All done
+	return 0;
+}
+