accumulate函数的问题

[mz126]

为什么写成模板函数就不能实现呢 最后两个输出全是0
求大神指教

#include <iostream>     // std::cout
#include <numeric>      // std::accumulate
#include <vector>

template< class T >
T sum_type( T* numbers , int n )
{
	T sum = 0.0;
	std ::accumulate( numbers , numbers + n , sum );
	return sum;
}

int main ( void ) 
{
	int init_int = 0;
	int numbers_int[] = {10,20,30};
	
	double init_double = 0.0;
	double numners_double[] = { 10.1 , 20.1 , 30.1 };
	
	std ::cout << std::accumulate( numbers_int , numbers_int+3 , init_int) << std ::endl;
	std ::cout << std::accumulate( numners_double , numners_double+3 , init_double) << std ::endl;
	
	std ::cout << sum_type( numbers_int , 3 ) << std ::endl; 
	std ::cout << sum_type( numners_double , 3 ) << std ::endl; 

	return 0;
}

[jiht594]

sum = std ::accumulate( numbers , numbers + n , sum ); return sum;

[mz126]

刚才看了下这个函数 原来第三个参数是值传递啊 多谢大神指导