霍夫曼解码程序问题

Question

我正在尝试编写一个霍夫曼解码算法。我决定采用迭代方法。我相信我遇到的主要问题与我的nodetype结构有关。在DDD中，它说没有正确的*孩子。有关为什么会这样的建议吗？我已经搜遍了所有问题并没有找到解决方法。有什么建议吗？

为简单起见，我省略了程序的其余部分。

#include <fstream>
#include <iostream>
#include <queue>
#include <iomanip>
#include <map>
#include <string>
#include <cassert>
#include <sstream>

using namespace std;
typedef unsigned int uint;

struct nodetype
{
  // constructor
  nodetype( char symbol, nodetype * left, nodetype * right) :
    symbol( symbol ), left( left ), right( right )
  { }

  char symbol;
  nodetype* left;
  nodetype* right;
};

void createDecodingTree(  nodetype* root,
                        nodetype* &iter, 
                        string &codeSubstring, 
                        char leaf )
{
string code = codeSubstring;
nodetype* newLeaf = new nodetype( leaf, NULL, NULL );

uint index = 0;
uint codeLength = code.length();
iter = root;
//traverse through the code until the second to last bit
//for( uint i = 0; i <= code.length()-1; i++ );
while( codeLength - 1 > 0 )
{
    if( code.at(index) == '0' )
    {
        if( iter->left == NULL )
        {
            nodetype* newLeft = new nodetype( '\0', NULL, NULL );
            iter->left = newLeft;
            iter = iter->left;
        }
        else{
            iter = iter->left;
        }
    }
    if( code.at(index) == '1' ) 
    {
        if( iter->right == NULL )
        {
            nodetype* newRight = new nodetype( '\0', NULL, NULL );
            iter->right = newRight;
            iter = iter->right;
        }
        else{
            iter = iter->right;
        }
    }
    codeLength--;
    index++;
}   
//now make a new leaf based on the last bit
if( code.at( code.length() - 1 ) == '0' )
    iter->left = newLeaf;
else{
    iter->right = newLeaf;
}
}

这就是我初始化root的方式。

nodetype* root = new nodetype( '\0', NULL, NULL );