[英]strcpy assertion error c++
我是一个学生,只是学习c ++,所以我确信有很多更有效的方法可以做到这一点。 如此说来,我真的很感谢能帮助我弄清楚程序为什么崩溃的帮助。 我将其范围缩小了一个strcpy函数,该函数崩溃并破坏了所有内容,并对其进行了注释和标记。 很明显,我在程序中多次使用具有相似参数的strcpy函数,因此我不明白为什么该特定程序会崩溃。 我已经尝试了所有我能想到的,并非常感谢您的帮助。 到目前为止,我有很多注释,因此它应该与名为“ bookdb”的正确文本文件一起运行,我的文本文件当前包含该文件
Active Learning Approach,Randal Albert,9780763757236,1,650,1,<br>
Technical Communications,John Lannon,9780321899972,2,724,0,
要查看错误,您必须取消注释strcpy(bookArray [num_books] .author_name,temp_authorName);
#define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <iomanip>
#include <fstream>
#include <cstring>
enum Genres {HORROR=1, SCIFI, COMEDY, DRAMA, ACTION};
struct Book
{
char title[100];
char author_name[50];
char isbn[14];
Genres genre;
int num_pages;
bool paperback;
};
//Function Declarations
unsigned short ReadBooks(Book * bookArray, unsigned short & num_books);
void DisplayBooks(Book * bookArray, unsigned short num_books);
void ResizeArrays(Book * bookArray, unsigned short num_books);
int main ()
{
unsigned short num_books = 0;
Book * bookArray = new Book();
num_books = ReadBooks(bookArray, num_books);
}//End Main
unsigned short ReadBooks(Book * bookArray, unsigned short & num_books)
{
ifstream readBooks("bookdb.txt");
char temp_title[100] = "0";
char temp_authorName[100] = "0";
char temp_isbn[14] = "0";
char temp_genre[50] = "0";
char temp_numPages[50] = "0";
char temp_paperback[50] = "0";
int genreNumber = 0,
numPages = 0,
paperback = 0;
if (readBooks.is_open() )
{
cout << "The file was successfully opened\n" << endl;
readBooks.getline(temp_title, 100, ',');//Reads into temp cstring
strcpy(bookArray[num_books].title, temp_title); //copies to dynamic cstring
//cout << bookArray[num_books].title << endl; //displays part of structure to make sure it worked!!
readBooks.getline(temp_authorName, 100, ',');
strcpy(bookArray[num_books].author_name, temp_authorName);
//cout << bookArray[num_books].author_name << endl;
readBooks.getline(temp_isbn, 14, ',');
strcpy(bookArray[num_books].isbn, temp_isbn);
//cout << bookArray[num_books].isbn << endl;
readBooks.getline(temp_genre, 50, ',');//Get the genre as a char
genreNumber = atoi(temp_genre);//converts char to an int
bookArray[num_books].genre = static_cast <Genres> (genreNumber);//converts int to ENUM
//cout << bookArray[num_books].genre << endl;//Displays ENUM to make sure it worked!!
readBooks.getline(temp_numPages, 50, ',');
numPages = atoi(temp_numPages); //converts char to an int
bookArray[num_books].num_pages = numPages; //assigns int to structure
//cout << bookArray[num_books].num_pages << endl; //Displays part of structure to make sure to works!!
readBooks.getline(temp_paperback, 50, ',');
paperback = atoi(temp_paperback); //converts char to an int
bookArray[num_books].paperback = static_cast <bool> (paperback);
//cout << bookArray[num_books].paperback << endl;
num_books++;
//DisplayBooks(bookArray, num_books);
ResizeArrays(bookArray, num_books);
cout << "The number of books is: " << num_books << endl;
//while (!readBooks.eof() )
//{
readBooks.getline(temp_title, 100, ',');//Reads into temp cstring
strcpy(bookArray[num_books].title, temp_title); //copies to dynamic cstring
cout << bookArray[num_books].title << endl; //displays part of structure to make sure it worked!!
readBooks.getline(temp_authorName, 100, ',');
cout << temp_authorName << endl;
//strcpy(bookArray[num_books].author_name, "0");
///THIS BREAKS MY CODE////strcpy(bookArray[num_books].author_name, temp_authorName);
//cout << bookArray[num_books].author_name << endl;
readBooks.getline(temp_isbn, 14, ',');
//strcpy(bookArray[num_books].isbn, temp_isbn);
//cout << bookArray[num_books].isbn << endl;
readBooks.getline(temp_genre, 50, ',');//Get the genre as a char
//genreNumber = atoi(temp_genre);//converts char to an int
//bookArray[num_books].genre = static_cast <Genres> (genreNumber);//converts int to ENUM
//cout << bookArray[num_books].genre << endl;//Displays ENUM to make sure it worked!!
readBooks.getline(temp_numPages, 1000, ',');
//numPages = atoi(temp_numPages); //converts char to an int
//bookArray[num_books].num_pages = numPages; //assigns int to structure
//cout << bookArray[num_books].num_pages << endl; //Displays part of structure to make sure to works!!
readBooks.getline(temp_paperback, 50, ',');
//paperback = atoi(temp_paperback); //converts char to an int
//bookArray[num_books].paperback = static_cast <bool> (paperback);
//cout << bookArray[num_books].paperback << endl;*/
num_books++;
//ResizeArrays(bookArray, num_books);
//}//End while
readBooks.close();
}//End if
else
{
cout << "There was not an existing book file, so one will be created" << endl;
}//End else
return 0;
}//End ReadBooks
void DisplayBooks(Book * bookArray, unsigned short num_books)
{
for (unsigned short i = 0; i < num_books; i++)
{
cout << setw(30) << left << bookArray[i].title << left << setw(20) << bookArray[i].author_name << left << setw(15) << bookArray[i].isbn
<< left << setw(3) << bookArray[i].genre << left<< setw(6) << bookArray[i].num_pages << left << setw(4) << bookArray[i].paperback << endl;
}//End For
}//ENd Display Function
void ResizeArrays(Book * bookArray, unsigned short num_books)
{
Book * temp_bookArray = new Book[num_books + 1];
for (int i = 0; i < num_books; i++)
{
strcpy(temp_bookArray[i].title, bookArray[i].title);
//cout << temp_bookArray[i].title << endl; //For Debugging
strcpy(temp_bookArray[i].author_name, bookArray[i].author_name);
//cout << temp_bookArray[i].author_name << endl; //for Debugging
strcpy(temp_bookArray[i].isbn, bookArray[i].isbn);
//cout << temp_bookArray[i].isbn << endl;//for debugging
temp_bookArray[i].genre = bookArray[i].genre;
//cout << temp_bookArray[i].genre << endl;//for debugging
temp_bookArray[i].num_pages = bookArray[i].num_pages;
//cout << temp_bookArray[i].num_pages << endl;// for debugging
temp_bookArray[i].paperback = bookArray[i].paperback;
//cout << temp_bookArray[i].paperback << endl; //for debugging
}//End for
delete [] bookArray;
bookArray = temp_bookArray;
DisplayBooks(bookArray, num_books); //debugging to make sure bookArray is reassigned
}//End Resize Function
strlen获取所有不带'\\ 0'的元素,因此如果您有str =“ 1234”; str的长度是5,(1234 +'\\ 0)但返回4.Strcpy取所有5个元素+'\\ 0'。
ResizeArrays存在问题:
只需将其修复到可以使用的程度,您可以执行以下操作:
Book* ResizeArrays(Book * bookArray, unsigned short num_books)
{
....
return bookArray;
}
然后以这种方式使用该功能
bookArray = ResizeArrays(bookArray, num_books);
但是,在使用数组删除时,对于第一次分配,还需要在main()中使用数组分配,
Book * bookArray = new Book[1];
即使只分配一本书,它也应该作为数组来完成,因此它与ResizeArrays中使用的delete []兼容。
我认为这是一项学习练习。 在C ++的正常使用中,您不会使用裸的new和delete运算符。 您可以简单地使用std :: vector或类似方法,或者创建一个将管理内存的对象,并分别在构造函数和析构函数中使用new和delete。
我看到的问题:
问题1
没有足够的空间来正确容纳ISBN。 输入文件中ISBN的长度为14个字符。 要将它们保存在以空终止的字符串中,您需要一个可以容纳15个或更多字符的数组。
结果,线
readBooks.getline(temp_isbn, 14, ',');
由于必须使用第14个字符来存储'\\0'
因此它将停止读取13个字符。
问题2
这条线看起来不正确。
readBooks.getline(temp_numPages, 1000, ',');
我怀疑这是一个错字,你的意思是
readBooks.getline(temp_numPages, 50, ',');
问题3
ResizeArray
的内存处理存在问题。
void ResizeArrays(Book * bookArray, unsigned short num_books)
{
Book * temp_bookArray = new Book[num_books + 1];
// Here, you are deleting the memory that was allocated in `main`.
// bookArray in the calling function now points to memory that has been
// deleted here.
delete [] bookArray;
// Here, you are changing the value of bookArray but only
// locally in this function. This assignment doesn't
// change the value of bookArray in the calling function.
bookArray = temp_bookArray;
DisplayBooks(bookArray, num_books); //debugging to make sure bookArray is reassigned
}//End Resize Function
如果将ResizeArray
更改为:
void ResizeArrays(Book*& bookArray, unsigned short num_books)
情况会更好。
问题4
我看到您已经注释掉ReadBooks
的while
循环。 如果您决定使该循环恢复活力,则必须在每次循环中调整bookArray
大小。
建议使用std::vector<Book*>
来保存书籍,而不是为Books
数组分配内存会更容易。
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