(C++) _algobase.h: Cannot convert 'const int' to 'MyClass *'

 

Compile error.

 

 

 

 

 

Full error message

 

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[C++ Error] _algobase.h(341): E2034 Cannot convert 'const int' to 'MyClass *'

 

 

 

 

 

Cause

 

The following code caused this compile error:

 

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#include <vector> struct MyClass {}; int main() {   const int size = 10; //Or other positive int   std::vector<MyClass*> v(size,0); }

 

IDE: C++ Builder 6.0

Compiler: Borland BCC32.EXE version 6.0.10.157

Project type: Console

 

The zero denotes that the MyClass pointer is uninitialized. The compiler, however, believes this zero denotes an integer value.

 

The code where the compiler takes you, in _algobase.h:

 

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template <class _OutputIter, class _Size, class _Tp> _STLP_INLINE_LOOP _OutputIter fill_n(_OutputIter __first, _Size __n, const _Tp& __value) {   _STLP_FIX_LITERAL_BUG(__first)   for ( ; __n > 0; --__n, ++__first)     *__first = __value; //THIS LINE   return __first; }

 

 

 

 

 

Solution

 

There are two options:

1. Change the first argument's data type to unsigned int
2. Cast the null in the second argument explicitly to a MyClass*

 

 

 

 

 

Change the first argument's data type to unsigned int

 

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#include <vector>   struct MyClass {};   int main() {   const unsigned int size = 10; //Or other value   std::vector<MyClass*> v(size,0); }

 

I would bet that the first argument's data type might also be std::size_t.

 

 

 

 

 

Cast the null in the second argument explicitly to a MyClass*

 

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#include <vector> struct MyClass {}; int main() {   const int size = 10; //Or other positive int   std::vector<MyClass*> v(size, static_cast<MyClass*>(0)); }