malloc( )：内存损坏(快速)错误C++
malloc( )：内存损坏(快速)错误C++
提问于 2014-10-26 02:34:17
我在C++工作。我正在研究一种方法来改变堆栈的最大容量，我对我正在得到的一个错误感到困惑。下面是我的方法。
void Stack::setCapacity(unsigned newCapacity){
if(newCapacity< this->getSize()){
throw StackException("setCapacity()",
"the size is larger than the desired capacity");
} else {
if(newCapacity != myCapacity){
Item * tempArray = new Item[newCapacity];
if(newCapacity < myCapacity){
for(unsigned i=0; i<newCapacity;i++){
tempArray[i] = myArray[i];
}
} else if (newCapacity > myCapacity) {
for(unsigned i=0; i<myCapacity; i++){
tempArray[i] = myArray[i];
}
}
for(unsigned i=0; i<newCapacity; i++){
myArray[i] = tempArray[i];
}
delete tempArray;
}
myCapacity = newCapacity;
}
}我还编写了一个测试方法来测试我的setCapacity( )方法是否有效。
void StackTester::setCapacityTest() {
cout << "- setCapacity... " << flush;
// empty stack
Stack st7(5);
assert(st7.getSize() == 0);
assert(st7.getCapacity() == 5);
st7.setCapacity(7);
assert(st7.getCapacity() == 7);
cout << " 1 " << flush;
// partially filled stack - larger capacity
Stack st8(5);
assert(st8.getCapacity() == 5);
st8.push(3);
st8.push(4);
st8.setCapacity(7);
assert(st8.getCapacity() == 7);
assert(st8.getTop() == 4);
st8.pop();
assert(st8.getTop() == 3);
cout << " 2 " << flush;
// size larger than new capacity
try{
Stack st9(3);
st9.push(7);
st9.push(4);
st9.push(11);
assert(st9.getSize() == 3);
st9.setCapacity(2);
cerr << "setCapacity's new capacity is larger than the size";
exit(1);
} catch(StackException& se){
cout << " 3 " << flush;
}
// partially filled stack - smaller capacity
Stack st10(5);
assert(st10.getCapacity() == 5);
st10.push(1);
st10.setCapacity(2);
assert(st10.getCapacity() == 2);
assert(st10.getTop() == 1);
cout << " 4 " << flush;
// fully filled stack - larger capacity
Stack st11(2);
assert(st11.getCapacity() == 2);
st11.push(3);
st11.push(7);
assert(st11.getTop() == 7);
st11.setCapacity(3);
assert(st11.getCapacity() == 3);
cout << " 5 " << flush;
cout << " Passed!" << endl;
}当我通过注释其他部分来单独运行测试的每个部分时，一切都很好。测试的每个部分都通过了。但是，当我组合这些部分并尝试运行整个测试时，我会得到以下错误：
* glibc检测到*/home/./StackProject: malloc()：内存损坏(快速)：0x0000000001e86030 *
使用调试器，我将问题的范围缩小到在堆栈中创建myArray。例如，在我的测试中成功运行“1”之后，在“2”中在myArray (5)中创建st8将导致程序崩溃。
我感到困惑的主要原因是，每一节都是个别通过的，但并不是集体通过的。我不知道该怎么办。我的方法写错了吗？如果是这样的话，我该如何纠正呢？
谢谢。
回答 2
Stack Overflow用户
回答已采纳
发布于 2014-10-26 04:07:28
在下面的代码块中，我看到了setCapacity中的以下问题：
if(newCapacity != myCapacity){
Item * tempArray = new Item[newCapacity];
if(newCapacity < myCapacity){
for(unsigned i=0; i<newCapacity;i++){
tempArray[i] = myArray[i];
}
} else if (newCapacity > myCapacity) {
for(unsigned i=0; i<myCapacity; i++){
tempArray[i] = myArray[i];
}
}
// When newCapacity > myCapacity, myArray does not
// have enough space for this loop.
// Say myCapacity = 5 and newCapacity = 7
// Accessing myArray[5] and myArray[6] is a problem.
for(unsigned i=0; i<newCapacity; i++){
myArray[i] = tempArray[i];
}
// You are deleting the newly allocated array, even though you are using
// the wrong delete operator.
// myArray still points to the old allocated memory.
delete tempArray;
}你需要的是：
if(newCapacity != myCapacity){
Item * tempArray = new Item[newCapacity];
if(newCapacity < myCapacity){
for(unsigned i=0; i<newCapacity;i++){
tempArray[i] = myArray[i];
}
} else if (newCapacity > myCapacity) {
for(unsigned i=0; i<myCapacity; i++){
tempArray[i] = myArray[i];
}
}
// Need to delete the old array and keep the new array.
Item* oldArray = myArray;
myArray = tempArray;
// Use the array delete operator, not the simple delete operator.
delete [] oldArray;
}Stack Overflow用户
发布于 2014-10-26 02:43:09
你有
delete tempArray;但是它是一个数组，所以你必须做：
delete [] tempArray;(虽然我不知道这个函数是做什么的，也不知道为什么.)
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/26569250
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