msdn bind2nd功能示例

Question

I am using MS VS 6.0 with SP 6 on Windows 7 64-bit. Win32 Console App. Still on VS 6.0, because I have to maintain legacy code. Most VS 6 things work without problems.

I was trying to learn about bind2nd by looking at: https://msdn.microsoft.com/en-us/library/3f0defz2.aspx

The code fails when compiled giving the error (among others): error C2955: 'iterator' : use of class template requires template argument list The code fails on the line after the comment below

How do I correct this code so that it compiles ?

The code is

#include <vector>  
#include <functional> 
#include <algorithm> 
#include <iostream> 

using namespace std; 

// Creation of a user-defined function object that inherits from 
// the unary_function base class 
class greaterthan15: unary_function<int, bool> 
{ 
public: 
    result_type operator()( argument_type i ) 
    { 
        return ( result_type )( i > 15 ); 
    } 
}; 

int main() 
{ 
    vector<int> v1; 
    vector<int>::iterator Iter; 

    int i; 
    for ( i = 0; i <= 5; i++ ) 
    { 
        v1.push_back( 5 * i ); 
    } 

    cout << "The vector v1 = ( "; 
    for ( Iter = v1.begin(); Iter != v1.end(); Iter++ ) 
        cout << *Iter << " "; 
    cout << ")" << endl; 

    // Count the number of integers > 10 in the vector 
    // COMPILE FAILS ON NEXT LINE 
    vector<int>::iterator::difference_type result1a; 
    result1a = count_if( v1.begin(), v1.end(), bind2nd( greater<int>(), 10 ) ); 
    cout << "The number of elements in v1 greater than 10 is: " 
        << result1a << "." << endl; 

    // Compare counting the number of integers > 15 in the vector with 
    // a user-defined function object 
    vector<int>::iterator::difference_type result1b; 
    result1b = count_if( v1.begin(), v1.end(), greaterthan15() ); 
    cout << "The number of elements in v1 greater than 15 is: " 
        << result1b << "." << endl; 

    // Count the number of integers < 10 in the vector 
    vector<int>::iterator::difference_type result2; 
    result2 = count_if( v1.begin(), v1.end(), bind1st(greater<int>(), 10 ) ); 
    cout << "The number of elements in v1 less than 10 is: " 
        << result2 << "." << endl; 

} 

Answer 1

I am in the lucky position of not having to use MSVC6 any more so I cannot check what I am suggesting, anyway try to turn

vector<int>::iterator::difference_type

into

vector<int>::difference_type