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首页 > 解决方案 > malloc: *** 对象 0x100519860 的错误：未分配被释放的指针 *** 在 malloc_error_break 中设置断点以进行调试

c++ - malloc: *** 对象 0x100519860 的错误：未分配被释放的指针 *** 在 malloc_error_break 中设置断点以进行调试

问题描述

我在编辑函数（unionSet）之前运行了这段代码，一旦我在编辑这个错误后运行了程序。我在 XCode 上使用 C++ 工作，但我之前还没有看到这个。

malloc：* 对象 0x100519860 的错误：未分配被释放的指针 *在 malloc_error_break 中设置断点以进行调试

#include "Set.hpp"
#include <string>
#include <sstream>
#include <cassert>

using namespace std;

// Function for the default constructor.
Set::Set()
{
    // default constructor
    theSet = new int[0];
};

// Function for the overloaded constructor taking an element and building an array for it.
Set::Set(int element)
{
    // take element
    // make one memory box
    // put element in that single box

    numElements = 1;
    theSet = new int[numElements];
    for(int i = 0; i < numElements; i++)
    theSet[i] = element;
};

// Function for the destructor.
Set::~Set()
{
    // deletes the dynamic array
    if (theSet != nullptr)
    {
        delete [] theSet;
        // removes the posibility of a dangling pointer
        theSet = nullptr;
    }
};

// Function building the copy constructor.
Set::Set(const Set& copy)
{
    // sets the value of copy constructor size equal to the current size by reference
    numElements = copy.numElements;

    // Allocate the memory.
    theSet = new int[numElements];

    // Copy all the data over.
    for (int i = 0; i < numElements; i++)
        theSet[i] = copy.theSet[i];
};

// Function for finding the elements in the intersection of set A and set B.
void Set::intersectSet(const Set& otherSet)
{
    // only the elements in both sets

    int *newSet = new int[otherSet.getCardinality()];
    int x = 0;

    for (int i = 0; i < 10; i++)
    {
        for (int j = 0; j < 10; j++){
            if (theSet[i] < otherSet.theSet[j])
            {
                i++;
            }

            else if (otherSet.theSet[j]< theSet[i])
            {
                j++;
            }

            else if (theSet[i] == otherSet.theSet[j])
            {
                theSet[i] = newSet[x];
                i++;
                j++;
                x++;
            }
            theSet = newSet;
        }
    }
};

// Function for finding the elements in the union of set A and set B.
void Set::unionSet(const Set& otherSet)
{
    // combine the two sets but no repeats

    theSet = otherSet.theSet;

}

// Function for retreiving the difference between set A and set B.
void Set::setDifference(const Set& otherSet)
{
    // the compliment of a set
    // an array with values from array A and only array A(cannot be in B)

    int *newSet = new int[otherSet.getCardinality()];
    int x = 0;

    for (int i = 0; i < 10; i++)
    {
        for (int j = 0; j < 10; j++){
            if (theSet[i] < otherSet.theSet[j])
            {
                i++;
                theSet[i] = newSet[x];
                x++;
            }

            else if (otherSet.theSet[j] < theSet[i])
            {
                j++;
            }

            else if (theSet[i] == otherSet.theSet[j])
            {
                i++;
                j++;
            }
            theSet = newSet;
        }
    }
};

// Function for checking if the "otherSet" is a subset of "theSet".
bool Set::isSubset(const Set& otherSet) const
{
    // all elements of a must be in set b to be a subset
    int i = 0, j = 0;
    for ( i = 0; i < numElements; i++)
    {
        for ( j = 0; j < numElements; j++)
        {
            if ( theSet[i] == theSet[j] )
                break;
        }

        if ( j == numElements)
            return false;
            // returns false if variable j is equal to the number of elements
    }
    return true;
    // return true if the statement is not changed
};

// Function for checking if the set is empty.
bool Set::isEmptySet() const
{
    // empty set = no memory
    if (theSet != nullptr)
        return false;
        // returns true if the set is empty
    return true;
        // returns false if the set is not empty
};

// Function for checking if an element is a member of the set.
bool Set::isMember(int element) const
{
    // check function looking for the element in the set
    for (int i = 0; i < numElements; ++i)
    {
        if (theSet[i] == element) return true;
        // returning true if the element is found
    }
    return false;
    // return false if element is not found
};

// Function for retreiving the number of elements in the set.
int Set::getCardinality() const
{
    // returns the size of the set over the first position
    return (sizeof(theSet)/sizeof(*theSet));
};

string Set::toString()
{
    // Builds the stream for output
    stringstream stream;

    // Opening stream statements when called
    stream << "{ ";

    // For loop for outputing the contents of set
    for (int i = 0; i < numElements; i++)
        stream << theSet[i] << ", ";
    // Closing stream statements
    stream << "}";

    // Returns the whole statement to the output location.
    return stream.str();
};

这段代码绝对是一项正在进行的工作，但如果不弄清楚错误发生的原因，我就无法继续前进。

测试文件如下所示：

#include <iostream>
#include "Set.hpp"
#include <string>

using namespace std;

// This function takes a method call as a string, a boolean value returned
// by a call and the expected boolean value and pretty prints the result.
void boolExpected(string method, bool val, bool expected)
{
    if (expected)
        cout << method << " = " << val << " expected true (1) ";
    else
        cout << method << " = " << val << " expected false (0) ";

    if (expected == val)
        cout << " [ PASS ]\n";
    else
        cout << " [ FAIL ]\n";
}

// This function takes a method call as a string, an integer value returned
// by a call and the expected integer value and pretty prints the result.
void intExpected(string method, int val, int expected)
{
    cout << method << " = " << val << " expected " << expected;
    if (expected == val)
        cout << " [ PASS ]\n";
    else
        cout << " [ FAIL ]\n";
}

// This function takes a method call as a string, an integer value returned
// by a call and the expected integer value and pretty prints the result.
void stringExpected(string method, string val, string expected)
{
    cout << method << " = " << val << " expected " << expected;
    if (expected == val)
        cout << " [ PASS ]\n";
    else
        cout << " [ FAIL ]\n";
}

// Tests the isEmptySet() method.
void testIsEmptySet()
{
    Set mySet;
    Set mySet2(3);

    // added to see contents of array
    cout << " mySet contains " << mySet.toString() << ". " << endl;
    cout << " mySet2 contains " << mySet2.toString() << ". " << endl;

    boolExpected("mySet.isEmptySet()", mySet.isEmptySet(), true);
    boolExpected("mySet2.isEmptySet()", mySet2.isEmptySet(), false);
}

// Tests the isMember() method.
void testIsMember()
{
    Set mySet;
    Set* tmp;

    // Build up a set.
    Set mySet2(3);

    tmp = new Set(4);
    mySet2.unionSet(*tmp);
    delete tmp;

    tmp = new Set(7);
    mySet2.unionSet(*tmp);
    delete tmp;

    // added to see what contents of array are
    cout << " mySet contains " << mySet.toString() << ". " << endl;
    cout << " mySet2 contains " << mySet2.toString() << ". " << endl;

    boolExpected("mySet.isMember(5)", mySet.isMember(5), false);
    boolExpected("mySet.isMember(7)", mySet.isMember(7), false);
    boolExpected("mySet2.isMember(7)", mySet2.isMember(7), true);
    boolExpected("mySet2.isMember(4)", mySet2.isMember(4), true);
    boolExpected("mySet2.isMember(3)", mySet2.isMember(3), true);
    boolExpected("mySet2.isMember(15)", mySet2.isMember(15), false);
}

// Tests the isSubset method.
void testIsSubset()
{
    Set mySet(7);
    Set* tmp;

    // Build up a set.
    Set mySet2(3);

    tmp = new Set(4);
    mySet2.unionSet(*tmp);
    delete tmp;

    tmp = new Set(7);
    mySet2.unionSet(*tmp);
    delete tmp;

    // added to see what contents of array are
    cout << " mySet contains " << mySet.toString() << ". " << endl;
    cout << " mySet2 contains " << mySet2.toString() << ". " << endl;

    boolExpected("mySet.isSubset(mySet2)", mySet.isSubset(mySet2), true);
    boolExpected("mySet2.isSubset(mySet)", mySet2.isSubset(mySet), false);
}

// Tests the getCardinality method.
void testGetCardinality()
{
    Set emptySet;
    Set mySet(7);
    Set* tmp;

    // Build up a set.
    Set mySet2(3);

    tmp = new Set(4);
    mySet2.unionSet(*tmp);
    delete tmp;

    tmp = new Set(7);
    mySet2.unionSet(*tmp);
    delete tmp;

    // added to see what contents of array are
    cout << " mySet contains " << mySet.toString() << ". " << endl;
    cout << " mySet2 contains " << mySet2.toString() << ". " << endl;

    intExpected("mySet.getCardinality()", mySet.getCardinality(), 1);
    intExpected("mySet2.getCardinality()", mySet2.getCardinality(), 3);
    intExpected("emptySet.getCardinality()", emptySet.getCardinality(), 0);
}

// Tests the unionSet method.
void testUnionSet()
{
    Set emptySet;
    Set mySet(7);
    Set* tmp;

    // Build up a set.
    Set mySet2(3);

    tmp = new Set(4);
    mySet2.unionSet(*tmp);
    delete tmp;

    stringExpected("{ 3 } union { 4 } ", mySet2.toString(), "{ 3, 4 }");

    tmp = new Set(7);
    mySet2.unionSet(*tmp);
    delete tmp;

    stringExpected("{ 3, 4 } union { 7 } ", mySet2.toString(), "{ 3, 4, 7 }");

    emptySet.unionSet(mySet);
    stringExpected("{ } union { 7 }", emptySet.toString(), "{ 7 }");
}

// This tests the intersectSet() method.
void testIntersectSet()
{
    Set emptySet;
    Set mySet(7);
    Set* tmp;

    // Build up a set.
    Set mySet2(3);

    tmp = new Set(4);
    mySet2.unionSet(*tmp);
    delete tmp;

    tmp = new Set(7);
    mySet2.unionSet(*tmp);
    delete tmp;

    emptySet.intersectSet(mySet);
    stringExpected("{ } intersect { 7 }", emptySet.toString(), "{ }");

    mySet.intersectSet(mySet2);
    stringExpected("{ 7 } intersect { 3, 4, 7 }", mySet.toString(), "{ 7 }");

    mySet2.intersectSet(mySet);
    stringExpected("{ 3, 4, 7 } intersect { 7 }", mySet2.toString(), "{ 7 }");
}

// This tests the setDifference method.
void testSetDifference()
{
    Set mySet(7);
    Set* tmp;

    // Build up a set.
    Set mySet2(3);

    tmp = new Set(4);
    mySet2.unionSet(*tmp);
    delete tmp;

    tmp = new Set(7);
    mySet2.unionSet(*tmp);
    delete tmp;

    mySet.setDifference(mySet2);
    stringExpected("{ 7 } difference { 3, 4, 7 }", mySet.toString(), "{ }");

    Set mySet3(7);

    mySet2.setDifference(mySet3);
    stringExpected("{ 3, 4, 7 } difference { 7 }", mySet2.toString(), "{ 3, 4 }");
}

int main()
{
    cout << "Testing isEmptySet()\n";
    cout << "--------------------\n";
    testIsEmptySet();
    cout << endl << endl;

    cout << "Testing isMember()\n";
    cout << "------------------\n";
    testIsMember();
    cout << endl << endl;

    cout << "Testing isSubset()\n";
    cout << "------------------\n";
    testIsSubset();
    cout << endl << endl;

    cout << "Testing getCardinality()\n";
    cout << "------------------------\n";
    testGetCardinality();
    cout << endl << endl;

    cout << "Testing unionSet()\n";
    cout << "------------------\n";
    testUnionSet();
    cout << endl << endl;

    cout << "Testing intersectSet()\n";
    cout << "----------------------\n";
    testIntersectSet();
    cout << endl << endl;


    cout << "Testing setDifference()\n";
    cout << "-----------------------\n";
    testSetDifference();
    cout << endl << endl;


    return 0;
}

输出在终端中显示为：

>Testing isEmptySet()
>--------------------
> mySet contains { }. 
> mySet2 contains { 3, }. 
>mySet.isEmptySet() = 0 expected true (1)  [ FAIL ]
>mySet2.isEmptySet() = 0 expected false (0)  [ PASS ]
>
>
>Testing isMember()
>------------------
> mySet contains { }. 
> mySet2 contains { 0, }. 
>mySet.isMember(5) = 0 expected false (0)  [ PASS ]
>mySet.isMember(7) = 0 expected false (0)  [ PASS ]
>mySet2.isMember(7) = 0 expected true (1)  [ FAIL ]
>mySet2.isMember(4) = 0 expected true (1)  [ FAIL ]
>mySet2.isMember(3) = 0 expected true (1)  [ FAIL ]
>mySet2.isMember(15) = 0 expected false (0)  [ PASS ]
>Set(13123,0x1003a8380) malloc: *** error for object 0x100519860: pointer being freed was not allocated
>*** set a breakpoint in malloc_error_break to debug

任何帮助是极大的赞赏。

标签： c++

解决方案

您的直接问题是由unionSet. 它不执行联合操作，并且您正在复制一个将被调用者删除的指针。释放的内存可能会在第二次被删除之前被重用。

您需要正确实施集合联合操作。

为避免将来出现问题，您还需要实现赋值运算符Set。

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