c++ - 子集程序之和

Question

我是 C++ 的新手，正在编写子集求和程序，该程序接受用户定义的一组数字，其中第一个数字被认为是总数。我已经尝试使用 DDD 来调试这个程序，但是我仍然遇到越界错误。我似乎无法找出为什么会这样。有什么线索吗？谢谢。这是错误:

terminate called after throwing an instance of 'std::out_of_range'
what(): vector::_M_range_check

代码:

#include <iostream>
#include <vector>
#include <cassert>
#include <iomanip>
#include <climits>
#include <math.h>
#include <algorithm>

typedef unsigned int uint;
using namespace std;

//////// Function declerations //////////
void sum_of_subsets( uint index, 
                     uint weight, 
                     uint total, 
                     vector<bool> &include, 
                     vector<uint> &w,
                     uint W );

bool promising ( uint index, 
                 uint weight, 
                 uint W, 
                 vector<uint> w,
                 uint total );

.

/////////////// Main //////////////////
int main()
{
    //string sortingCode = "-as";
    vector<uint> w;             // vector of weights
    vector<bool> include;       
        uint W;                     // the total
    uint index = 0;
    uint weight = 0;            // the current weight of subsets
    uint total = 0;             // the superset total weight
    while( ! cin.eof() )
  {
    uint value;
    if( cin >> value && ! cin.eof() )
      w.push_back( value );
  }

    W = w.front();
    w.erase( w.begin() );
    // instantiate the include vector to false
    for( uint k = 0; k <= w.size(); k++ )
        include.push_back(0);
    // calculate the superset total
    for( uint k = 0; k <= w.size()-1; k++ )
        total += w.at(k);
    // calculate the sum of subsets accordig to CL argument
    sum_of_subsets( index, weight, total, include, w, W );

    // report success   
    return 0;
}    

.

////////// Function Bodies ///////////
void sum_of_subsets( uint index, 
                     uint weight, 
                     uint total, 
                     vector<bool> &include, 
                     vector<uint> &w, 
                     uint W )
{    
    cout << "inside sumb_of_subsets" << endl;
    if( promising(index, weight, W, w, total) )
    {   
        cout << "promising is true, continue" << endl;
        if( weight == W )
        {   
            for( uint k = 0; k <= index; k++ )
            {
                if(include.at(k))
                    cout << w.at(k) << " ";;
            }
            cout << endl;
        }
        else
        {
            include.at(index + 1) = 1;
            cout << "index1 = " << index << endl;
            sum_of_subsets( index + 1, 
                            weight + w.at(index + 1 ), 
                            total - w.at(index + 1),
                            include, w, W ) ;
            include.at(index + 1) = 0;
            cout << "index2 = " << index << endl;
            sum_of_subsets( index + 1, 
                            weight, 
                            total - w.at(index + 1),
                            include, w, W );
        }
    }
}

.

bool promising ( uint index, 
                 uint weight, 
                 uint W, 
                 vector<uint> w,
                 uint total )
{    
    cout << "inside promising" << endl;
    cout << "W = " << W << endl;
    cout << "weight = " << weight << endl;
    return ( weight + total >= W )
         && ( (weight == W) || (weight + w.at(index+1) <= W));
}

Answer 1

这个错误:

terminate called after throwing an instance of 'std::out_of_range'
what(): vector::_M_range_check

表明您的 vector 调试版本正在抛出异常，但没有捕获到它。发生这种情况时，程序会立即终止而不展开堆栈，这会使调试变得更加困难。

更改为:

// calculate the sum of subsets accordig to CL argument
try
{
  sum_of_subsets( index, weight, total, include, w, W );
}
catch (...)
{
  cout << "put breakpoint here!" << endl;
}

在 catch 中添加一个断点，并检查回溯以查看您的代码的哪一部分出错了。