debug醒目：new delete实现出现溢出

[DraculaW]

#include <iostream>
#include <fstream>
#include <string>
#include <cstdlib>

using namespace std;

const int INITIAL_LIST_CAPACITY = 10;

void build_wordlist (string* word_list, int capacity, string filename)
{

ifstream words;
string word;
int size = 0;

// Allocate the space for the word list
word_list = new string[INITIAL_LIST_CAPACITY];
capacity = INITIAL_LIST_CAPACITY;

// Open the file
words.open (filename.c_str());

if (!words)
{
cerr << "Could not open " << filename << endl;
exit(EXIT_FAILURE);
}

// Loop to read in words
words >> word;
while (! words.eof())
{

// If there isn't enough space, grow the array and copy the contents
if (size > (capacity-1))
{

// Create another array that is twice as large as the word_list
string new_word_list = *(new string[2 * capacity]);

// Copy the words from the word_list into the new array
for (int index=0; (index < capacity); index++)
{
new_word_list = word_list[index];
}

delete word_list;
* word_list = new_word_list;

capacity *=2;
}

// Save the word
word_list[size] = word;
size++;

// Read in next word
words >> word;
}

words.close();
}

int main (int argc, char *argv[]) {

// An array of string objects to store our
// word list.
string *word_list=NULL;
int capacity = 0;

// Read the word list file
build_wordlist (word_list, capacity, "words.txt");

// Print out the words
for (int index=0; (index < capacity) && (word_list[index] != "");
index++)
{
cout << word_list[index] << endl;
}

return EXIT_SUCCESS;
}

在同一目录下有一个word文件里面包含有二十多个单词

运行后出现溢出错误

[oo]

发多个一样的帖子，小心被咔嚓掉

[yjh1982]

delete word_list;
改用delete []word_list;

[hongjun_han]

build_wordlist (word_list, capacity, "words.txt"); 不能实现内存分配，
建议使用返回值
另外像 string new_word_list = *(new string[2 * capacity]); 这种语句也太搞笑了吧。

另外capacity的改变不会返回给 主程序，不知你是怎么运行的。
毛病太多了
建议用 Vector 重写一个。

[goodluckyxl]

void build_wordlist (string*& word_list//引用, int& capacity,//引用 string filename)
//引用否则不能修改内容

[DraculaW]

不是啊


这个是实验课作业

要求debug来的

[hongjun_han]

试试这个

#include <iostream>
#include <fstream>
#include <string>
#include <cassert>
#include <cstdlib>


using namespace std;

const int INITIAL_LIST_CAPACITY = 10;

void* build_wordlist (string* word_list, int& capacity, string filename)
{

ifstream words;
string word;
int size = 0;

// Allocate the space for the word list
word_list = new string[INITIAL_LIST_CAPACITY];
capacity = INITIAL_LIST_CAPACITY;

// Open the file
words.open (filename.c_str());

if (!words)
{
cerr << "Could not open " << filename << endl;
exit(EXIT_FAILURE);
}

// Loop to read in words
words >> word;
while (! words.eof())
{

// If there isn't enough space, grow the array and copy the contents
if (size > (capacity-1))
{

// Create another array that is twice as large as the word_list
//string new_word_list = *(new string[2 * capacity]);
string* new_word_list = new string[2 * capacity];
if (new_word_list == NULL)
{
cerr << " error " << endl;
system("pause");
}
// Copy the words from the word_list into the new array
for (int index=0; (index < capacity); index++)
{
new_word_list[index] = word_list[index];
}

delete[] word_list;
word_list = new_word_list;
new_word_list = NULL;

capacity *=2;
}

// Save the word
word_list[size] = word;
size++;

// Read in next word
words >> word;
}

words.close();
return word_list;
}

int main (int argc, char *argv[]) {

// An array of string objects to store our
// word list.
string *word_list=NULL;
int capacity = 10;

// Read the word list file
word_list = (string*)build_wordlist (word_list, capacity, "words.txt");
cout << "cpacity is " << capacity << endl;
// Print out the words
for (int index=0; (index < capacity) && (word_list[index] != "");
index++)
{
cout << *word_list << endl;
}

system("pause");

return EXIT_SUCCESS;
}

[hongjun_han]

把这个
for (int index=0; (index < capacity) && (word_list[index] != "");
index++)
{
cout << *word_list << endl;
}
换成
cout << *word_list << endl;

[DraculaW]

谢谢六楼

不过输出好像不够哦

输出的是：
capacity is 40
/*然后是
23个*/
one

[DraculaW]

但是words里面是：
one
two
three
four
five
six
seven
eight
nine
ten
eleven
twelve
thirteen
fourteen
fifteen
sixteen
seventeen
eighteen
nineteen
twenty
twenty-one
twenty-two
twenty-three
twenty-four
twenty-five

[xuzheng318]

用delete []word_list;

[hongjun_han]

#include <iostream>
#include <fstream>
#include <string>
#include <cassert>
#include <cstdlib>


using namespace std;

const int INITIAL_LIST_CAPACITY = 10;
/*
string readString(const ifstream& words)
{
char ch=0x00；
string str = "";

while(ch!=0x0a)
{
words>>ch;
str += ch;
}
return str;
}

*/
void* build_wordlist (string* word_list, int& capacity, string filename)
{

ifstream words;
string word;
int size = 0;

// Allocate the space for the word list
word_list = new string[INITIAL_LIST_CAPACITY];
capacity = INITIAL_LIST_CAPACITY;

// Open the file
words.open (filename.c_str());

if (!words)
{
cerr << "Could not open " << filename << endl;
exit(EXIT_FAILURE);
}

// Loop to read in words
words >> word;
while (! words.eof())
{

// If there isn't enough space, grow the array and copy the contents
if (size > (capacity-1))
{

// Create another array that is twice as large as the word_list
//string new_word_list = *(new string[2 * capacity]);
string* new_word_list = new string[2 * capacity];
if (new_word_list == NULL)
{
cerr << " error " << endl;
system("pause");
}
// Copy the words from the word_list into the new array
for (int index=0; (index < capacity); index++)
{
new_word_list[index] = word_list[index];
}


delete[] word_list;
word_list = new_word_list;
new_word_list = NULL;

capacity *=2;
}

// Save the word
word_list[size] = word;
size++;

// Read in next word
words >> word;
capacity = size;
// word = readString(words);
}

words.close();

return word_list;
}

int main (int argc, char *argv[]) {

// An array of string objects to store our
// word list.
string *word_list= new string[10];
int capacity = 10;

// Read the word list file
word_list = (string*)build_wordlist (word_list, capacity, "words.txt");
cout << "cpacity is " << capacity << endl;

// Print out the words
for(int i=0;i<capacity;i++){

cout << word_list[i] << endl;
}

system("pause");

return EXIT_SUCCESS;
}
快结帖

[hongjun_han]

这个你看 没问题了吧，没问题就揭帖吧

[hongjun_han]

老大 你还不揭帖，难道还不满意吗？？？
你这种人我看没救了，以后还想让我给你回帖吗？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？///////////////////////////////////////////////？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？？

[DraculaW]

不好意思哈


我刚才下课了