我的代码有什么问题？ 我的程序无法编译

Question

Ok, so my assignment is to build on an existing code from the book. I have to add the 3rd box and then calculate the total for all 3 boxes. Here is what I've written so far, but it will not compile. Please help me find the problem. Thanks.

The program I'm using is MS Visual C++ and the complile error I get is

error C2447: '{' : missing function header (old-style formal list?)

referring to the { after my int Total_Volume line

// Structures_and_classes.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
using std::cout;
using std::endl;
class CBox // Class definition at global scope
{
public:
 double m_Length; // Length of a box in inches
 double m_Width; // Width of a box in inches
 double m_Height; // Height of a box in inches
};
int main();
int Total_Volume;
{
CBox box1;
CBox box2;
CBox box3;
 double boxVolume = 0.0;             // Stores the volume of a box
  box1.m_Height = 18.0;            // Define the values
  box1.m_Length = 78.0;             // of the members of
  box1.m_Width = 24.0;              // the object box1
  box2.m_Height = box1.m_Height - 10;         // Define box2     Box 2 H = 8
  box2.m_Length = box1.m_Length/2.0;          // members in    Box 2 L = 39
  box2.m_Width = 0.25*box1.m_Length;           // terms of box1  Box 2 W = 6
  box3.m_Height = box1.m_Height + 2;         // Define box3     Box 3 H = 20
  box3.m_Length = box1.m_Length - 18;          //members in    Box 3 L = 50
  box3.m_Width = box1.m_Width + 1;           //terms of box1   Box 3 W = 25 

  // Box1
  boxVolume = box1.m_Height*box1.m_Length*box1.m_Width;cout << endl;
<< "Volume of box1 = " << boxVolume;
  cout << endl;
  // Box 2
  boxVolume = box2.m_Height*box2.m_Length*box2.m_Width;cout << endl;
<< "Volume of box2 = " << boxVolume;
  cout << endl;
  // Box 3
  boxVolume = box3.m_Height*box3.m_Length*box3.m_Width;cout << endl;
<< "Volume of box3 = " << boxVolume;
  cout << endl;

//Calculate Total Volume
  Total_Volume = (box1.m_Height*box1.m_Length*box1.m_Width)+
      (box2.m_Height*box2.m_Length*box2.m_Width)+
      (box3.m_Height*box3.m_Length*box3.m_Width);

return 0;
}

Answer 1

Change:

int main();
int Total_Volume;
{

to:

int main()
{
    int Total_Volume;

That will fix your immediate problem, although I suspect you'll have a few more questions today :-)

The actual problem with your current code is that it defines a prototype for main, followed by a file-level variable, followed by a naked brace, which is why it's complaining about a missing function header.

You may also want to consider changing your main function to one of:

int main (int argc, char *argv[])
int main (void)

(probably the second in your case) as these are the two forms required to be supported by the ISO C standard. Implementations are free to accept others if they wish but I usually prefer my code to be as standard as possible. The reason I say "may" is because it's not necessarily required to get your code working, more of a style thing.

Answer 2

int main();
int Total_Volume;
{

should be

int main()
{
  int Total_Volume;

Answer 3

It looks like you mixed up a couple lines:

int main();
int Total_Volume;
{
CBox box1;
CBox box2;
CBox box3;

looks like it should be:

int main() {
  int Total_Volume;
  CBox box1;
  CBox box2;
  CBox box3;

Answer 4

Try moving

int Total_Volume;

after the {

Answer 5

Goodness me. Please check the preview and at least make sure your question looks like prose plus some code. Edit okay, let's assume that was a glitch that's been sorted out. The rest of my answer still holds.

A little bit of digging suggests the first problem is that you don't have a properly defined main() function. This is the first thing one learns about C++ typically, so in the first instance get that right.

Good luck.

Answer 6

You probably intended to write:

int main()
{
     int TotalVolume;

You can't start a block where you did. You have declared that there will be a function main() , and that there's a global variable TotalVolume, but the anonymous block following these is not allowed.