3.7. Getting the Minimum and Maximum Values for a Numeric Type


You need to know the largest or smallest representable value for your platform for a numeric type, such as an int or double.


Use the numeric_limits class template in the <limits> header to get, among other things, the largest and smallest possible values for a numeric type (see Example 3-9).

Example 3-9. Getting numeric limits

#include <iostream>
#include <limits>

using namespace std;

template<typename T>
void showMinMax() {
   cout << "min: " << numeric_limits<T>::min() << endl;
   cout << "max: " << numeric_limits<T>::max() << endl;
   cout << endl;

int main() {

   cout << "short:" << endl;
   cout << "int:" << endl;
   cout << "long:" << endl;
   cout << "float:" << endl;
   cout << "double:" << endl;
   cout << "long double:" << endl;
   showMinMax<long double>();
   cout << "unsigned short:" << endl;
   showMinMax<unsigned short>();
   cout << "unsigned int:" << endl;
   showMinMax<unsigned int>();
   cout << "unsigned long:" << endl;
   showMinMax<unsigned long>();

Here’s what I get on Windows XP using Visual C++ 7.1:

short: min: -32768 max: 32767 int: min: -2147483648 max: 2147483647 long: min: -2147483648 max: 2147483647 float: min: 1.17549e-038 max: 3.40282e+038 double: min: 2.22507e-308 max: 1.79769e+308 long double: min: 2.22507e-308 max: 1.79769e+308 unsigned short: min: 0 max: 65535 unsigned int: min: 0 max: 4294967295 unsigned long: ...

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