* String and Char in function template
@ 2004-08-31 22:06 learning c++
0 siblings, 0 replies; only message in thread
From: learning c++ @ 2004-08-31 22:06 UTC (permalink / raw)
To: gcc-help
Hi, Everyone:
I have a short code about function template like this:
#include <iostream>
#include <string>
using std::cout;
template <typename T> // template parameter list
T const &greater(T const &first, T const &second)
{
return (first > second) ? first : second;
}
int main()
{
int a = 1, b = 2;
cout << greater(a, b) << '\n';
long c = 4L, d = 3L;
cout << greater(c, d) << '\n';
double e = 5.62, f = 3.48;
cout << greater(e, f) << '\n';
char g = 'A', h = 'a';
cout << greater(g, h) << '\n';
std::string two("two"), three("three");
cout << greater(two, three) << '\n';
char const *two("two"), *three("three");
cout << greater(two, three) << '\n';
char const *two("two"), *three("three");
cout << greater(two, three) << '\n';
return 0;
}
when I compile it, the errors are the following:
/v/dunix51_alpha/gnu/gcc/lib/gcc-lib/alphaev5-dec-osf5/3.3/include/c++/bits/stl_function.h:
In
function `int main()':
/v/dunix51_alpha/gnu/gcc/lib/gcc-lib/alphaev5-dec-osf5/3.3/include/c++/bits/stl_function.h:188:
error: `
template<class _Tp> struct std::greater' is not a function,
greater.cpp:7: error: conflict with `template<class T> const T&
greater(const
T&, const T&)'
greater.cpp:22: error: in call to `greater'
greater.cpp:23: error: conflicting types for `const char*two'
greater.cpp:21: error: previous declaration as `std::string two'
greater.cpp:23: error: conflicting types for `const char*three'
greater.cpp:21: error: previous declaration as `std::string three'
greater.cpp:23: warning: statement with no effect
greater.cpp:23: confused by earlier errors, bailing out
What is wrong with my code? In addition, I hope to know something about
"const" in "char const *two("two"), *three("three");" and the difference
between "using std::cout;" and "using namespace std;"
Thanks in advance!
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