main.cpp

斯坦福Energy211/CME211课《c++编程——地球科学科学家和工程师》的课件

#include <iostream>

#include "vector.h"

using namespace std;

// This function sums the array of length doubles pointed 
// to by d, and then sets the first element equal to the
// sum.  This function is passed a Vector object, but the
// Vector class' double * conversion function is used to
// allow the Vector to be treated as an ordinary array
void test( double *d, int length )
{
	double sum = 0.0;
	for ( int i = 0; i < length; i++ )
		sum += d[i];
	d[0] = sum;
	cout << sum << endl;
}

int main() {
	
	try
	{
		// Create empty vector
		Vector v;
		cout << "empty v = \n";
		cout << v;
	
		// Use , operator to add elements
		v = ( v, 1.0 );
		v = ( v, 2.0 );
		cout << "new v = \n";
		cout << v;
		
		// test expects an array, but passing a Vector is
		// allowed because it supplies a function for 
		// converting to a double *
		test( v, v.get_length() );
		// test actually modifies the first element in the 
		// array it is passed, and this change is reflected 
		// in v too
		cout << "updated v = \n";
		cout << v;
		
		// The function call operator is overloaded to allow
		// passing a double argument, which is treated as an
		// "index" into the vector that actually linearly
		// interpolates between the values at the nearest
		// integer indices
		cout << "v(0.5) = " << v( 0.5 ) << endl;
		
		// Add more elements
		v = ( v, 3.0 );
		v = ( v, 8.0 );
		cout << "updated v = \n" << v;
		
		// Extract a subvector containing 1st & 3rd elements
		int p[] = { 0, 2 };
		cout << "v([ 0 2 ]) = \n" << v( p, 2 );
		
		// Create a 1-element vector from a double
		Vector w = 4.0;
		cout << "w = \n" << w;
	
		// Because 3 is an int, the other Vector constructor
		// is used, so an uninitialized vector of length 3
		// is created
		Vector z = 3;
		cout << "z = \n" << z;
		
		// Fill in elements
		z[0] = -5;
		z[1] = -4;
		z[2] = -3;
		cout << "z = \n" << z;	
		
		// Concatenate vectors using , operator
		Vector x = ( v, z );
		cout << "x = \n" << x;
		
	}
	catch(...) {
		cout << "An exception was thrown.\n";
	}
	
	return 0;
}