珍爱生命远离c++就是这么来的

1.#include"stdio.h"

2.#include"sparsepp-master/sparsepp.h"

3.int main()

4.{

5. spp::sparse_hash_map,int> mp;

6.mp.insert(std::make_pair(std::make_pair(1,1),1));

7.return 0;

8.}

这个程序时使用sparsepp库提供的hash版map来存数据的例子,但他有一个错误:库中并没有给出为std::pair产生hash值的算法,因此该程序不能工作。

理想情况下我们想要编译器这么提示我们:“亲爱的程序员,您的程序这里有错,错误原因和解决方法我都给你标注好了,么么嗒~~~”

具体错误提示大概长这样:

line 6:mp.insert(std::make_pair(std::make_pair(1,1),1));

                                ^^^^^^^^^^^^^^^^^^^ can't generate serialization

但实际上有点困难,一般编译器只会这么提示我们:“吔屎啦,这里这里这里这里这里这里我都看不懂,赶紧给老娘改!”

JAVA和javascript就喜欢这么干,错误提示大概长这样:

In file sparsepp-master/sparsepp.h:1483:42: XXXXXX

In file sparsepp-master/sparsepp.h:5069:77: XXXXXX

In file main.cpp:6:25: type cast failed

In file main.cpp:3:1: XXXXX

而混乱邪恶的C++是这样提示我们的:

In file included from main.cpp:2:0:

sparsepp-master/sparsepp.h: In instantiation of 'size_t spp::spp_hash::operator()(const T&) const [with T = std::pair; size_t = long long unsigned int]':

sparsepp-master/sparsepp.h:1483:42:  required from 'size_t spp::sparsehash_internal::sh_hashtable_settings::hash(const key_type&) const [with Key = std::pair; HashFunc = spp::spp_hash >; SizeType = long long unsigned int; int HT_MIN_BUCKETS = 4; size_t = long long unsigned int; spp::sparsehash_internal::sh_hashtable_settings::key_type = std::pair]'

sparsepp-master/sparsepp.h:4729:31:  required from 'size_t spp::sparse_hashtable::hash(const key_type&) const [with Value = std::pair, int>; Key = std::pair; HashFcn = spp::spp_hash >; ExtractKey = spp::sparse_hash_map, int>::SelectKey; SetKey = spp::sparse_hash_map, int>::SetKey; EqualKey = std::equal_to >; Alloc = spp::libc_allocator_with_realloc, int> >; size_t = long long unsigned int; spp::sparse_hashtable::key_type = std::pair]'

sparsepp-master/sparsepp.h:4242:33:  required from 'spp::sparse_hashtable::Position spp::sparse_hashtable::_find_position(const key_type&) const [with Value = std::pair, int>; Key = std::pair; HashFcn = spp::spp_hash >; ExtractKey = spp::sparse_hash_map, int>::SelectKey; SetKey = spp::sparse_hash_map, int>::SetKey; EqualKey = std::equal_to >; Alloc = spp::libc_allocator_with_realloc, int> >; spp::sparse_hashtable::key_type = std::pair]'

sparsepp-master/sparsepp.h:4401:38:  required from 'std::pair::other>::ne_iterator, bool> spp::sparse_hashtable::_insert_noresize(T&) [with T = const std::pair, int>; Value = std::pair, int>; Key = std::pair; HashFcn = spp::spp_hash >; ExtractKey = spp::sparse_hash_map, int>::SelectKey; SetKey = spp::sparse_hash_map, int>::SetKey; EqualKey = std::equal_to >; Alloc = spp::libc_allocator_with_realloc, int> >; typename spp::sparsetable::other>::ne_iterator = spp::Two_d_iterator, int>, spp::sparsegroup, int>, spp::libc_allocator_with_realloc, int> > >*, std::pair, int>*, std::bidirectional_iterator_tag>]'

sparsepp-master/sparsepp.h:4451:36:  required from 'std::pair::other>::ne_iterator, bool> spp::sparse_hashtable::insert(spp::sparse_hashtable::const_reference) [with Value = std::pair, int>; Key = std::pair; HashFcn = spp::spp_hash >; ExtractKey = spp::sparse_hash_map, int>::SelectKey; SetKey = spp::sparse_hash_map, int>::SetKey; EqualKey = std::equal_to >; Alloc = spp::libc_allocator_with_realloc, int> >; typename spp::sparsetable::other>::ne_iterator = spp::Two_d_iterator, int>, spp::sparsegroup, int>, spp::libc_allocator_with_realloc, int> > >*, std::pair, int>*, std::bidirectional_iterator_tag>; spp::sparse_hashtable::const_reference = const std::pair, int>&; spp::sparse_hashtable::value_type = std::pair, int>]'

sparsepp-master/sparsepp.h:5069:77:  required from 'std::pair::type, T>, Key, HashFcn, spp::sparse_hash_map::SelectKey, spp::sparse_hash_map::SetKey, EqualKey, Alloc>::iterator, bool> spp::sparse_hash_map::insert(const value_type&) [with Key = std::pair; T = int; HashFcn = spp::spp_hash >; EqualKey = std::equal_to >; Alloc = spp::libc_allocator_with_realloc, int> >; typename spp::sparse_hashtable::type, T>, Key, HashFcn, spp::sparse_hash_map::SelectKey, spp::sparse_hash_map::SetKey, EqualKey, Alloc>::iterator = spp::Two_d_iterator, int>, spp::sparsegroup, int>, spp::libc_allocator_with_realloc, int> > >*, std::pair, int>*, std::bidirectional_iterator_tag>; spp::sparse_hash_map::value_type = std::pair, int>]'

main.cpp:6:49:  required from here

sparsepp-master/sparsepp.h:943:27: error: use of deleted function 'std::hash >::hash()'

        SPP_HASH_CLASS hasher;

                          ^~~~~~

In file included from E:/mingw-w64/x86_64-6.3.0-posix-seh-rt_v5-rev2/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/bits/basic_string.h:5628:0,

                from E:/mingw-w64/x86_64-6.3.0-posix-seh-rt_v5-rev2/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/string:52,

                from sparsepp-master/sparsepp.h:839,

                from main.cpp:2:

E:/mingw-w64/x86_64-6.3.0-posix-seh-rt_v5-rev2/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/bits/functional_hash.h:85:12: note: 'std::hash >::hash()' is implicitly deleted because the default definition would be ill-formed:

    struct hash : __hash_enum<_Tp>

            ^~~~

E:/mingw-w64/x86_64-6.3.0-posix-seh-rt_v5-rev2/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/bits/functional_hash.h:85:12: error: no matching function for call to 'std::__hash_enum, false>::__hash_enum()'

E:/mingw-w64/x86_64-6.3.0-posix-seh-rt_v5-rev2/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/bits/functional_hash.h:66:7: note: candidate: std::__hash_enum<_Tp, >::__hash_enum(std::__hash_enum<_Tp, >&&) [with _Tp = std::pair; bool = false]

      __hash_enum(__hash_enum&&);

      ^~~~~~~~~~~

E:/mingw-w64/x86_64-6.3.0-posix-seh-rt_v5-rev2/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/bits/functional_hash.h:66:7: note:  candidate expects 1 argument, 0 provided

E:/mingw-w64/x86_64-6.3.0-posix-seh-rt_v5-rev2/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/bits/functional_hash.h:85:12: error: 'std::__hash_enum<_Tp, >::~__hash_enum() [with _Tp = std::pair; bool = false]' is private within this context

    struct hash : __hash_enum<_Tp>

            ^~~~

E:/mingw-w64/x86_64-6.3.0-posix-seh-rt_v5-rev2/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/bits/functional_hash.h:67:7: note: declared private here

      ~__hash_enum();

      ^

In file included from main.cpp:2:0:

sparsepp-master/sparsepp.h:943:27: error: use of deleted function 'std::hash >::~hash()'

        SPP_HASH_CLASS hasher;

                          ^~~~~~

In file included from E:/mingw-w64/x86_64-6.3.0-posix-seh-rt_v5-rev2/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/bits/basic_string.h:5628:0,

                from E:/mingw-w64/x86_64-6.3.0-posix-seh-rt_v5-rev2/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/string:52,

                from sparsepp-master/sparsepp.h:839,

                from main.cpp:2:

E:/mingw-w64/x86_64-6.3.0-posix-seh-rt_v5-rev2/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/bits/functional_hash.h:85:12: note: 'std::hash >::~hash()' is implicitly deleted because the default definition would be ill-formed:

    struct hash : __hash_enum<_Tp>

            ^~~~

E:/mingw-w64/x86_64-6.3.0-posix-seh-rt_v5-rev2/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/bits/functional_hash.h:85:12: error: 'std::__hash_enum<_Tp, >::~__hash_enum() [with _Tp = std::pair; bool = false]' is private within this context

E:/mingw-w64/x86_64-6.3.0-posix-seh-rt_v5-rev2/mingw64/lib/gcc/x86_64-w64-mingw32/6.3.0/include/c++/bits/functional_hash.h:67:7: note: declared private here

      ~__hash_enum();

      ^

In file included from main.cpp:2:0:

sparsepp-master/sparsepp.h:944:22: error: no match for call to '(std::hash >) (const std::pair&)'

        return hasher(__v);

                ~~~~~~^~~~~

☻☺这只是一段代码报错时候弹出的提示,当你想像一下一句话报错就能出现这么长的代码,当一个程序出现问题的时候,你找个错误都得找半天,所以大部分人都会选择修复bug然后就出现了更多的bug。

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