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?如何查看各個類型的最大值 收藏
問題源于同事的一個問題，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，但是看不到浮點數的最大值。浮點數的最大值可以這樣得到:

#include <iostream>

#include <limits>

using namespace std;

// compile with: /EHscint main(){

?? cout << numeric_limits<double>::max() << endl;?

}

運行平臺為VS2008,如果出現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
//
//??? 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;
}請運行相關的代碼查看結果。

本文來自CSDN博客，轉載請標明出處：http://blog.csdn.net/bichenggui/archive/2009/08/26/4488072.aspx