在我的链表实现中使用valgrind检查内存泄漏，给我的确是“丢失：1个块中40字节”

Question

我正在尝试实现链表。类insertLast()中的方法linkedListType之一导致错误

这里是linkedList.hpp文件中的功能

template<class dataType>                                  
void linkedListType<dataType>::insertLast(dataType data)  
{                                                         
  nodeType<dataType> *newNode = new nodeType<dataType>(); 
  newNode->info =data;                                    
  if (first==NULL) insertFirst(data);                     
  else{                                                   
    newNode->link=NULL;                                   
    last->link=newNode;                                   
    last=newNode;                                         
  }                                                       
}                                                         

template<class dataType>                    
void linkedListType<dataType>::destroyList()
{                                           
  nodeType<dataType> *temp;                 
  while(first!=NULL){                       
    temp = first;                           
    first=first->link;                      
    delete temp;                            
  }                                         
  last=NULL;                                
  count=0;                                  
}                                                                                     

template<class dataType>                                  
void linkedListType<dataType>::insertFirst(dataType data) 
{                                                         
  nodeType<dataType> *newNode = new nodeType<dataType>(); 
  newNode->info=data;                                     
  if (first==NULL){                                       
    first=newNode;                                        
    last=newNode;                                         
  }                                                       
  else{                                                   
    newNode->link=first;                                  
    first=newNode;                                        
  }                                                       
}                                                                                                                  

这里是main功能

#include <iostream>                                       
#include "linkedList.hpp"                                 
using namespace std;                                      
int main()                                                
{                                                         
  linkedListType<string> names;                           
  int numOfNames;                                         
  cout<<"\nEnter the number of names: ";cin>>numOfNames;  
  string name;                                            
  for(int i=0; i<numOfNames;i++) {                        
    cin>>name;                                            
    names.insertLast(name);                               
  }                                                       
  names.destroyList();                                    
}                                                                                                                                                               

当我使用命令时：

valgrind --leak-check=full ./a.out

==5528== Command: ./a.out
==5528== 

Enter the number of names: 2
xyv
fds
==5528== 
==5528== HEAP SUMMARY:
==5528==     in use at exit: 40 bytes in 1 blocks
==5528==   total heap usage: 6 allocs, 5 frees, 74,872 bytes allocated
==5528== 
==5528== 40 bytes in 1 blocks are definitely lost in loss record 1 of 1
==5528==    at 0x4C3017F: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==5528==    by 0x108F45: linkedListType<std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::insertLast(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) (in /home/abdo/cpp/linkedList/a.out)

==5528== 
==5528== LEAK SUMMARY:
==5528==    definitely lost: 40 bytes in 1 blocks
==5528==    indirectly lost: 0 bytes in 0 blocks
==5528==      possibly lost: 0 bytes in 0 blocks
==5528==    still reachable: 0 bytes in 0 blocks
==5528==         suppressed: 0 bytes in 0 blocks
==5528== 
==5528== For counts of detected and suppressed errors, rerun with: -v
==5528== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

它给我一个错误，所以我的代码有什么问题吗？

Answer 1

您需要更改insertLast功能：

template<class dataType>                                  
void linkedListType<dataType>::insertLast(dataType data)  
{     
    if ( !first ) insertFirst( data );                   
    else
    { 
         nodeType<dataType> *newNode = new nodeType<dataType>(); 
         newNode->info =data;                                                    
         newNode->link=NULL;                                   
         last->link=newNode;                                   
         last=newNode;                                         
    }                                                       
}