c++ - 检查内存泄漏？

Question

对于我的代码，expand就是把vector的容量加倍。它应该为动态分配的数组动态重新分配内存并更新容量值，同时不会造成内存泄漏。

我想知道您将如何检查内存泄漏，因为我的测试没有显示 Visual Studio 中的执行时间。

void IntVector::expand(){
    cap = cap * 2;
    int *data2;
    data2 = data;
    IntVector::~IntVector();
    data = new int[cap];
    data = data2;
    delete data2;
}

header(我知道你不应该使用 namespace std)。

#ifndef INTVECTOR_H
#define INTVECTOR_H

using namespace std;
class IntVector{
private:
    unsigned sz;
    unsigned cap;
    int *data;
public:
    IntVector();
    IntVector(unsigned size);
    IntVector(unsigned size, int value);
    unsigned size() const;
    unsigned capacity() const;
    bool empty() const;
    const int & at (unsigned index) const;
    const int & front() const;
    const int & back() const;
    ~IntVector();
    void expand();

};

#endif

主文件

#include "IntVector.h"
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;



IntVector::IntVector(){
    sz = 0;
    cap = 0;
    data = NULL;
}

IntVector::IntVector(unsigned size){
    sz = size;
    cap = size;
    data = new int[sz];
    *data = 0;
}

IntVector::IntVector(unsigned size, int value){
    sz = size;
    cap = size;
    data = new int[sz];
    for(int i = 0; i < sz; i++){
        data[i] = value;
    }
}

unsigned IntVector::size() const{
    return sz;
}

unsigned IntVector::capacity() const{
    return cap;
}

bool IntVector::empty() const{
    if(sz > 0){
        return false;
    }
    else{
        return true;
    }
}

const int &IntVector::at(unsigned index) const{
    if(index > sz){
        exit(1);
    }
    else{
        return data[index];
    }
}

const int &IntVector::front() const{
    return data[0];
}

const int &IntVector::back() const{
    return data[sz];
}

IntVector::~IntVector(){
    delete data;
}

void IntVector::expand(){
    cap = cap * 2;
    int *data2;
    data2 = data;
    IntVector::~IntVector();
    data = new int[cap];
    data = data2;
    delete data2;
}

编辑:

void IntVector::expand(){
    cap = cap * 2;
    int *data2 = data;
    data = new int[cap];
    delete[] data2;
    delete data2;
}

Answer 1

这两行:

data = new int[cap];
data = data2;

分配一个整数数组，然后立即覆盖指向它的指针，从而永远失去分配的内存。那是内存泄漏。

使用 valgrind 或类似工具应该很容易导致这些错误。