va_arg會導致std :: bad_alloc

Question

每當我運行我的程序時，我都會得到一個std::bad_alloc異常，導致中止發生。只有在調用va_arg時纔會引發std::bad_alloc。奇怪的是，教師提供的崩潰代碼。我沒有寫下那條崩潰的路線。 Valgrind告訴我這是由new/new[]造成的。爲什麼va_arg造成這種情況？ bad_alloc只在執行時發生（它也在其他地方執行）。

void Library::addKeywordsForItem(const Item* const item, int nKeywords, ...) 
{ 
    // the code in this function demonstrates how to handle a vararg in C++ 

    va_list   keywords; 
    string   keyword = "test"; 
    bool   successFlag = false; 
    sArray   keywordV; 
    cout << "Before lookupItem\n"; 
    Item*   item2 = lookupItem(item); 
    cout << "After lookupItem\n"; 

    va_start(keywords, nKeywords); 
    cout << "after va_start\n"; 
    for (int i = 0; i < nKeywords; i++) //this code adds the items to a map of set to create a fast access structure for keyword searches 
    { 
     cout << "before keyword assign\n"; 
     keyword = va_arg(keywords, string); //Crash here 
     cout << "after keyword assign\n"; 
     // do something with each keyword 
     cout << "before HERE\n"; 
     keywordV.push_back(keyword); //pushes keyword onto vector 
     cout << "HERE\n"; 
     successFlag = addToSMap(item, keyword, keywordDbase); //This function is literally a copy/paste of the code 
     //originally designed for this function 
    } 
    va_end(keywords); 

    //Sets in keywords 
    item2->setKeywords(keywordV); 

    if(!successFlag) //Should never execute 
     cout << "This code reeks verily of wrongness.\n"; 
} 

上面的代碼是從下面的代碼教練書面線稱爲

library->addKeywordsForItem(item, 2, "autism", "Asperger's Syndrome"); 

這裏有錯誤，我得到

Valgrind的

**5851** new/new[] failed and should throw an exception, but Valgrind 
**5851** cannot throw exceptions and so is aborting instead. Sorry. 
==5851== at 0x4C275AC: ??? (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so) 
==5851== by 0x4C27DC6: operator new(unsigned long) (in /usr/lib64/valgrind/vgpreload_memcheck-amd64-linux.so) 
==5851== by 0x4F57496: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_assign(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (basic_string.tcc:265) 
==5851== by 0x4F577E8: std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::operator=(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const&) (basic_string.h:1181) 
==5851== by 0x4085F8: Library::addKeywordsForItem(Item const*, int, ...) (Library.cpp:79) 
==5851== by 0x401BB5: main (Asgmt04.cpp:38) 

計劃

終止扔「的std :: bad_alloc的」的一個實例後調用
什麼（）的std :: bad_alloc的中止

教員設計，它使用va_args（我剛填充它做什麼的循環）所以我不確定他的代碼爲什麼導致崩潰。我的代碼是否導致這個崩潰？有人可以借鑑一些見解嗎？

Answer 1

"autism"和"Asperger's Syndrome"是const char *值，而不是string價值，所以想讀他們爲string小號原因未定義的行爲。