template<typename T> const T& min(const T& a, const T& b) { return (a < b) ? a : b; }
int z = min<int>(i, j);
int z = min(i, j);
int z = min(x, j); // x is a double
int z = min<double>(x, j);
template<typename T, typename U> const T& min(const T& a, const U& b) { return (a < b) ? a : b; }
//: C05:StringConv.h // Function templates to convert to and from strings. #ifndef STRINGCONV_H #define STRINGCONV_H #include <string> #include <sstream> template<typename T> T fromString(const std::string& s) { std::istringstream is(s); T t; is >> t; return t; } template<typename T> std::string toString(const T& t) { std::ostringstream s; s << t; return s.str(); } #endif // STRINGCONV_H ///:~
Listado 6.13. C05/StringConv.h
//: C05:StringConvTest.cpp #include <complex> #include <iostream> #include "StringConv.h" using namespace std; int main() { int i = 1234; cout << "i == \"" << toString(i) << "\"" << endl; float x = 567.89; cout << "x == \"" << toString(x) << "\"" << endl; complex<float> c(1.0, 2.0); cout << "c == \"" << toString(c) << "\"" << endl; cout << endl; i = fromString<int>(string("1234")); cout << "i == " << i << endl; x = fromString<float>(string("567.89")); cout << "x == " << x << endl; c = fromString<complex<float> >(string("(1.0,2.0)")); cout << "c == " << c << endl; } ///:~
Listado 6.14. C05/StringConvTest.cpp
i == "1234" x == "567.89" c == "(1,2)" i == 1234 x == 567.89 c == (1,2)
//: C05:ImplicitCast.cpp template<typename R, typename P> R implicit_cast(const P& p) { return p; } int main() { int i = 1; float x = implicit_cast<float>(i); int j = implicit_cast<int>(x); //! char* p = implicit_cast<char*>(i); } ///:~
Listado 6.15. C05/ImplicitCast.cpp
//: C05:ArraySize.cpp #include <cstddef> using std::size_t; template<size_t R, size_t C, typename T> void init1(T a[R][C]) { for(size_t i = 0; i < R; ++i) for(size_t j = 0; j < C; ++j) a[i][j] = T(); } template<size_t R, size_t C, class T> void init2(T (&a)[R][C]) { // Reference parameter for(size_t i = 0; i < R; ++i) for(size_t j = 0; j < C; ++j) a[i][j] = T(); } int main() { int a[10][20]; init1<10,20>(a); // Must specify init2(a); // Sizes deduced } ///:~
Listado 6.16. C05/ArraySize.cpp