ISO C++ forbids delcaration of 'parameter' with no type

[fsshl]

Dear c++ expert:

I am using gnu/g++ 4.5.2
to compile a piece of code(page 423 of book(C++ cookbook))(that book claim these
programs in examples can compiled in visualc++ on window xp) on linux.

matrix.hpp:29:25: error: ‘valarray’ does not name a type
matrix.hpp:29:25: error: ISO C++ forbids declaration of ‘parameter’ with no type

template<typename T>
explicit matrix(const valarray<T>& x) // line 29

plz help and thanks a lot in advance

[Moschops]

#include <valarray>

[fsshl]

that book's example source code do include valarray
I tried again
this time I
g++ matrix.hpp
it generate same error as before
but then I
g++ matrix.cpp
it is compiled

anyway thanks your reply

[fsshl]

but the run result is not what book predict
----------------------------------
#include "matrix.hpp"

#include <iostream>

using namespace std;

int main( ) {
matrix<int> m(2,2);
m = 0;
m[0][0] = 1;
m[1][1] = 1;
m *= 2;
cout << "(" << m[0][0] << "," << m[0][1] << ")" << endl;
cout << "(" << m[1][0] << "," << m[1][1] << ")" << endl;
}
---------------------------------------------------------------
#ifndef MATRIX_HPP
#define MATRIX_HPP

#include "stride_iter.hpp" // see <link linkend="cplusplusckbk-CHP-11-SECT-12">Recipe 11.12</link>

#include <valarray>
#include <numeric>
#include <algorithm>

template<class Value_T>
class matrix
{
public:
// public typedefs
typedef Value_T value_type;
typedef matrix self;
typedef value_type* iterator;
typedef const value_type* const_iterator;
typedef Value_T* row_type;
typedef stride_iter<value_type*> col_type;
typedef const value_type* const_row_type;
typedef stride_iter<const value_type*> const_col_type;

// constructors
matrix( ) : nrows(0), ncols(0), m( ) { }
matrix(int r, int c) : nrows(r), ncols(c), m(r * c) { }
matrix(const self& x) : m(x.m), nrows(x.nrows), ncols(x.ncols) { }

template<typename T>
explicit matrix(const valarray<T>& x)
: m(x.size( ) + 1), nrows(x.size( )), ncols(1)
{
for (int i=0; i<x.size( ); ++i) m[i] = x[i];
}

// allow construction from matricies of other types
template<typename T>
explicit matrix(const matrix<T>& x)
: m(x.size( ) + 1), nrows(x.nrows), ncols(x.ncols)
{
copy(x.begin( ), x.end( ), m.begin( ));
}

// public functions
int rows( ) const { return nrows; }
int cols( ) const { return ncols; }
int size( ) const { return nrows * ncols; }

// element access
row_type row_begin(int n) { return &m[n * cols( )]; }
row_type row_end(int n) { return row_begin( ) + cols( ); }
col_type col_begin(int n) { return col_type(&m[n], cols( )); }
col_type col_end(int n) { return col_begin(n) + cols( ); }
const_row_type row_begin(int n) const { return &m[n * cols( )]; }
const_row_type row_end(int n) const { return row_begin( ) + cols( ); }
const_col_type col_begin(int n) const { return col_type(&m[n], cols( )); }
const_col_type col_end(int n) const { return col_begin( ) + cols( ); }
iterator begin( ) { return &m[0]; }
iterator end( ) { return begin( ) + size( ); }
const_iterator begin( ) const { return &m[0]; }
const_iterator end( ) const { return begin( ) + size( ); }

// operators
self& operator=(const self& x) {
m = x.m; nrows = x.nrows; ncols = x.ncols; return *this;
}
self& operator=(value_type x) { m = x; return *this; }
row_type operator[](int n) { return row_begin(n); }
const_row_type operator[](int n) const { return row_begin(n); }
self& operator+=(const self& x) { m += x.m; return *this; }
self& operator-=(const self& x) { m -= x.m; return *this; }
self& operator+=(value_type x) { m += x; return *this; }
self& operator-=(value_type x) { m -= x; return *this; }
self& operator*=(value_type x) { m *= x; return *this; }
self& operator/=(value_type x) { m /= x; return *this; }
self& operator%=(value_type x) { m %= x; return *this; }
self operator-( ) { return -m; }
self operator+( ) { return +m; }
self operator!( ) { return !m; }
self operator~( ) { return ~m; }

// friend operators
friend self operator+(const self& x, const self& y) { return self(x) += y; }
friend self operator-(const self& x, const self& y) { return self(x) -= y; }
friend self operator+(const self& x, value_type y) { return self(x) += y; }
friend self operator-(const self& x, value_type y) { return self(x) -= y; }
friend self operator*(const self& x, value_type y) { return self(x) *= y; }
friend self operator/(const self& x, value_type y) { return self(x) /= y; }
friend self operator%(const self& x, value_type y) { return self(x) %= y; }
private:
mutable valarray<Value_T> m;
int nrows;
int ncols;
};

#endif
---------------------------------------------------------------------------------
my result is
(1, 1)
(1, 1)
but book expect
(2 0)
(0 2)
plz help