http://blog.csdn.net/bichenggui/article/details/4488072
2009
問題源于同事的一個(gè)問題，VC編譯器里如何查看double的最大值? 他在limits.h里沒找到。
在limits.h里面，只可以看到整型的最大值，但是看不到浮點(diǎn)數(shù)的最大值。浮點(diǎn)數(shù)的最大值可以這樣得到:
#include <iostream>
#include <limits>
using namespace std;
// compile with: /EHsc
int main(){
cout << numeric_limits<double>::max() << endl;
}
運(yùn)行平臺(tái)為VS2008,如果出現(xiàn)max編譯沖突，可以加上#undef max。
模板類numeric_limits的聲明是:
template <typename T>
numeric_limits<T>
// 變量和成員函數(shù)//// 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()//////////////////////////////////////////////////////////////////////
實(shí)例代碼：
#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;}
請(qǐng)運(yùn)行相關(guān)的代碼查看結(jié)果。
聯(lián)系客服
