Illustrates how to use the members of the numeric_limits class in Visual C++.
To reference one of the members of this class, you need to specify the type that you want to obtain information about and the member name. The return will either be a value of 1 for true or 0 for false. For example, numeric_limits<int>::min will return the minimum value for an int.
备注
Some of the members are valid only for certain types. Please refer to the Online Help to determine if a member is valid only for a certain type.
Example
// Numeric.cpp
// compile with: /EHsc
//
// Variables and Functions:
//
// has_denorm
// has_denorm_loss
// has_infinity
// has_quiet_NaN
// has_signaling_NaN
// is_bounded
// is_exact
// is_iec559
// is_integer
// is_modulo
// is_signed
// is_specialized
// tinyness_before
// traps
// round_style
// digits
// digits10
// max_exponent
// max_exponent10
// min_exponent
// min_exponent10
// radix;
// denorm_min()
// epsilon()
// infinity()
// max()
// min()
// quiet_ NaN()
// round_error()
// signaling_NaN()
//////////////////////////////////////////////////////////////////////
#include <iostream>
#include <limits>
using namespace std;
int main() {
cout << " 1 The minimum value for char is " <<
(int)numeric_limits<char>::min() << endl;
cout << " 2 The minimum value for int is " <<
numeric_limits<int>::min() << endl;
cout << " 3 The maximum value for char is " <<
(int)numeric_limits<char>::max() << endl;
cout << " 4 The maximum value for int is " <<
numeric_limits<int>::max() << endl;
cout << " 5 The number of bits to represent a char is " <<
numeric_limits<char>::digits << endl;
cout << " 6 The number of bits to represent an int is " <<
numeric_limits<int>::digits << endl;
cout <<" 7 The number of digits representable in base 10 for float is "
<< numeric_limits<float>::digits10 << endl;
cout << " 8 Is a char signed? " <<
numeric_limits<char>::is_signed << endl;
cout << " 9 Is an unsigned integer signed? " <<
numeric_limits<unsigned int>::is_signed << endl;
cout << "10 Is an integer an integer? " <<
numeric_limits<int>::is_integer << endl;
cout << "11 Is a float an integer? " <<
numeric_limits<float>::is_integer << endl;
cout << "12 Is an integer exact? " <<
numeric_limits<int>::is_exact << endl;
cout << "13 Is a float exact? " <<
numeric_limits<float>::is_exact << endl;
cout << "14 The radix for float is " <<
numeric_limits<float>::radix << endl;
cout << "15 The epsilon for float is " <<
numeric_limits<float>::epsilon() << endl;
cout << "16 The round error for float is " <<
numeric_limits<float>::round_error() << endl;
cout << "17 The minimum exponent for float is " <<
numeric_limits<float>::min_exponent << endl;
cout << "18 The minimum exponent in base 10 " <<
numeric_limits<float>::min_exponent10 << endl;
cout << "19 The maximum exponent is " <<
numeric_limits<float>::max_exponent << endl;
cout << "20 The maximum exponent in base 10 " <<
numeric_limits<float>::max_exponent10 << endl;
cout << "21 Can float represent positive infinity? " <<
numeric_limits<float>::has_infinity << endl;
cout << "22 Can double represent positive infinity? " <<
numeric_limits<double>::has_infinity << endl;
cout << "23 Can int represent positive infinity? " <<
numeric_limits<int>::has_infinity << endl;
cout << "24 Can float represent a NaN? " <<
numeric_limits<float>::has_quiet_NaN << endl;
cout << "25 Can float represent a signaling NaN? " <<
numeric_limits<float>::has_signaling_NaN << endl;
cout << "26 Does float allow denormalized values? " <<
numeric_limits<float>::has_denorm << endl;
cout << "27 Does float detect denormalization loss? " <<
numeric_limits<float>::has_denorm_loss << endl;
cout << "28 Representation of positive infinity for float " <<
numeric_limits<float>::infinity() << endl;
cout << "29 Representation of quiet NaN for float " <<
numeric_limits<float>::quiet_NaN() << endl;
cout << "30 Minimum denormalized number for float " <<
numeric_limits<float>::denorm_min() << endl;
cout << "31 Minimum positive denormalized value for float " <<
numeric_limits<float>::denorm_min() << endl;
cout << "32 Does float adhere to IEC 559 standard? " <<
numeric_limits<float>::is_iec559 << endl;
cout << "33 Is float bounded? " <<
numeric_limits<float>::is_bounded << endl;
cout << "34 Is float modulo? " <<
numeric_limits<float>::is_modulo << endl;
cout << "35 Is int modulo? " <<
numeric_limits<float>::is_modulo << endl;
cout << "36 Is trapping implemented for float? " <<
numeric_limits<float>::traps << endl;
cout << "37 Is tinyness detected before rounding? " <<
numeric_limits<float>::tinyness_before << endl;
cout << "38 What is the rounding style for float? " <<
(int)numeric_limits<float>::round_style << endl;
cout << "39 What is the rounding style for int? " <<
(int)numeric_limits<int>::round_style << endl;
cout << "40 How does a float represent a signaling NaN? " <<
numeric_limits<float>::signaling_NaN() << endl;
cout << "41 Is int specialized? " <<
numeric_limits<float>::is_specialized << endl;
}
Output
1 The minimum value for char is -128 2 The minimum value for int is -2147483648 3 The maximum value for char is 127 4 The maximum value for int is 2147483647 5 The number of bits to represent a char is 7 6 The number of bits to represent an int is 31 7 The number of digits representable in base 10 for float is 6 8 Is a char signed? 1 9 Is an unsigned integer signed? 0 10 Is an integer an integer? 1 11 Is a float an integer? 0 12 Is an integer exact? 1 13 Is a float exact? 0 14 The radix for float is 2 15 The epsilon for float is 1.19209e-007 16 The round error for float is 0.5 17 The minimum exponent for float is -125 18 The minimum exponent in base 10 -37 19 The maximum exponent is 128 20 The maximum exponent in base 10 38 21 Can float represent positive infinity? 1 22 Can double represent positive infinity? 1 23 Can int represent positive infinity? 0 24 Can float represent a NaN? 1 25 Can float represent a signaling NaN? 1 26 Does float allow denormalized values? 1 27 Does float detect denormalization loss? 1 28 Representation of positive infinity for float 1.#INF 29 Representation of quiet NaN for float 1.#QNAN 30 Minimum denormalized number for float 1.4013e-045 31 Minimum positive denormalized value for float 1.4013e-045 32 Does float adhere to IEC 559 standard? 1 33 Is float bounded? 1 34 Is float modulo? 0 35 Is int modulo? 0 36 Is trapping implemented for float? 1 37 Is tinyness detected before rounding? 1 38 What is the rounding style for float? 1 39 What is the rounding style for int? 0 40 How does a float represent a signaling NaN? 1.#QNAN 41 Is int specialized? 1
Requirements
Header: <limits>