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POWhy do I get "must be modifiable l-value" compiler error (C2105) on following code?
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2013-10-31T19:55:43.903
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<p>I'm stumped by this one...the compiler outputs:</p> <p>d:\data\personal\projects\test\test.cpp(42): error C2105: '--' needs l-value</p> <pre><code>#include <iostream> #include <algorithm> #include <iterator> class FOO { public: typedef int* iterator; typedef const int* const_iterator; class explicit_iterator : public std::iterator< std::bidirectional_iterator_tag, int > { public: explicit_iterator(int* ptr = nullptr) : m_ptr(ptr) {} bool operator ==(const explicit_iterator& rhs) const { return m_ptr == rhs.m_ptr; } bool operator !=(const explicit_iterator& rhs) const { return m_ptr != rhs.m_ptr; } reference operator *() const { return *m_ptr; } explicit_iterator& operator ++() { ++m_ptr; return *this; } explicit_iterator& operator --() { --m_ptr; return *this; } private: int* m_ptr; }; FOO(int val = 0) { std::fill( begin(), end(), val ); } iterator begin() { return m_data; } iterator end() { return m_data + 10; } explicit_iterator begin2() { return explicit_iterator( begin() ); } explicit_iterator end2() { return explicit_iterator( end() ); } private: int m_data[10]; }; int main (int, char *[]) { FOO foo; // This is the line that fails! (Not this one, the one right below!!!) std::copy( foo.begin(), --foo.end(), std::ostream_iterator<int>( std::cout, "\n" ) ); // C2105 // All these variants are good std::copy( foo.begin2(), --foo.end2(), std::ostream_iterator<int>( std::cout, "\n" ) ); // good std::copy( foo.begin(), foo.end() - 1, std::ostream_iterator<int>( std::cout, "\n" ) ); // good int* end = foo.end(); std::copy( foo.begin(), --end, std::ostream_iterator<int>( std::cout, "\n" ) ); // good return 0; } </code></pre>
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<c++><compiler-errors><iterator>
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Why do I get "must be modifiable l-value" compiler error (C2105) on following code?
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