Data types that supports std::numeric_limits() in C++
The numeric_limits class template provides an easy and standardized way to query various properties of arithmetic types. For example, the maximum value a type T can store is std::numeric_limits<T>::max().
Example:
- std::numeric_limits<int>::max() gives the maximum possible value we can store in type int.
- std::numeric_limits<unsigned int>::max()) gives the maximum possible value we can store in type unsigned int.
The numeric_limits have many member functions, member constants, and helper classes and some of them are type-specific. For example std::numeric_limits<T>::lowest() for floating data types only. The most common queries for data types are:
- std::numeric_limits<T>::is_integer: It is true if T is numerical type and false for floating-point types.
- std::numeric_limits<T>::is_signed: It is true for all signed arithmetic types T and false for the unsigned types.
- std::numeric_limits<T>::digits: It is the number of digits in base-radix. For example- -1 for bool, 7 for char, 31 for int, etc.
- std::numeric_limits<T>::digits10: It is the number of base-10 digits that can be represented by the type T without any change.
- std::numeric_limits<T>::max_digits10: It is the number of base-10 digits that are necessary to uniquely represent all distinct values of the type T.
- Also, queries for a min, max, lowest, size in bytes, and bits.
The floating points have epsilon-related queries. Except for these, numeric_limits some more functions. For Example: has_infinity, traps, round_error, etc.
Below is the program to show the most common numeric_limits functions for all data types:
C++
// C++ program to demonstrate the use// possible numerical data types// that supports std::numeric_limits#include <cstdint>#include <functional>#include <iomanip>#include <iostream>#include <limits>#include <string>struct RowPrinter { // Left alignment int m_left; // Right alignment int m_right; RowPrinter(int left, int right) : m_left(left), m_right(right) { // Print bool as 'true' or 'false' // instead of 0 or 1. std::cout << std::boolalpha; } template <class A> auto printRow(const std::string& label, const A& value) const -> void { std::cout << std::setw(m_left) << label << std::setw(m_right) << value << "\n"; }};#define SHOW_INTEGER_LIMITS(numtype) \ showNumericLimits<numtype>(#numtype)#define SHOW_FLOAT_LIMITS(numtype) \ showFloatPointLimits<numtype>(#numtype)// Function to show the numeric// limitstemplate <class T>void showNumericLimits(const std::string& name){ RowPrinter rp{ 30, 25 }; std::cout << "Numeric limits for type: " << name << "\n"; std::cout << std::string(60, '-') << "\n"; rp.printRow("Type:", name); rp.printRow("Is integer:", std::numeric_limits<T>::is_integer); rp.printRow("Is signed:", std::numeric_limits<T>::is_signed); rp.printRow("Number of digits:", std::numeric_limits<T>::digits); rp.printRow("Number of digits 10:", std::numeric_limits<T>::digits10); rp.printRow("Max Number of digits 10:", std::numeric_limits<T>::max_digits10); // RTTI - Run-Time Type Information if (typeid(T) == typeid(uint8_t) || typeid(T) == typeid(int8_t) || typeid(T) == typeid(bool) || typeid(T) == typeid(char) || typeid(T) == typeid(unsigned char)) { // Min Abs - smallest positive value // for float point numbers rp.printRow("Min:", static_cast<int>( std::numeric_limits<T>::min())); // Smallest value (can be negative) rp.printRow("Lowest:", static_cast<int>( std::numeric_limits<T>::lowest())); // Largest value rp.printRow("Max:", static_cast<int>( std::numeric_limits<T>::max())); } else { rp.printRow("Min:", std::numeric_limits<T>::min()); rp.printRow("Lowest:", std::numeric_limits<T>::lowest()); rp.printRow("Max:", std::numeric_limits<T>::max()); } rp.printRow("Size in bytes:", sizeof(T)); rp.printRow("Size in bits:", 8 * sizeof(T)); std::cout << "\n";}// Function to show float points// limitstemplate <class T>void showFloatPointLimits(const std::string& name){ RowPrinter rp{ 30, 25 }; showNumericLimits<T>(name); rp.printRow("Epsilon:", std::numeric_limits<T>::epsilon()); rp.printRow("Min exponent:", std::numeric_limits<T>::min_exponent10); rp.printRow("Max exponent:", std::numeric_limits<T>::max_exponent10);}// Driver Codeint main(){ // Boolean type SHOW_INTEGER_LIMITS(bool); // Character types SHOW_INTEGER_LIMITS(char); SHOW_INTEGER_LIMITS(unsigned char); SHOW_INTEGER_LIMITS(wchar_t); // Standard integers in <cstdint> SHOW_INTEGER_LIMITS(int8_t); SHOW_INTEGER_LIMITS(uint8_t); SHOW_INTEGER_LIMITS(int16_t); SHOW_INTEGER_LIMITS(uint16_t); SHOW_INTEGER_LIMITS(int32_t); SHOW_INTEGER_LIMITS(uint32_t); SHOW_INTEGER_LIMITS(int64_t); SHOW_INTEGER_LIMITS(uint64_t); // Integer types SHOW_INTEGER_LIMITS(short); SHOW_INTEGER_LIMITS(unsigned short); SHOW_INTEGER_LIMITS(int); SHOW_INTEGER_LIMITS(unsigned int); SHOW_INTEGER_LIMITS(long); SHOW_INTEGER_LIMITS(unsigned long); SHOW_INTEGER_LIMITS(long long); SHOW_INTEGER_LIMITS(unsigned long long); // Floating types SHOW_FLOAT_LIMITS(float); SHOW_FLOAT_LIMITS(double); SHOW_FLOAT_LIMITS(long double); return 0;} |
Output:
Numeric limits for type: bool
------------------------------------------------------------
Type: bool
Is integer: true
Is signed: false
Number of digits: 1
Number of digits 10: 0
Max Number of digits 10: 0
Min: 0
Lowest: 0
Max: 1
Size in bytes: 1
Size in bits: 8
Numeric limits for type: char
------------------------------------------------------------
Type: char
Is integer: true
Is signed: true
Number of digits: 7
Number of digits 10: 2
Max Number of digits 10: 0
Min: -128
Lowest: -128
Max: 127
Size in bytes: 1
Size in bits: 8
Numeric limits for type: unsigned char
------------------------------------------------------------
Type: unsigned char
Is integer: true
Is signed: false
Number of digits: 8
Number of digits 10: 2
Max Number of digits 10: 0
Min: 0
Lowest: 0
Max: 255
Size in bytes: 1
Size in bits: 8
Numeric limits for type: wchar_t
------------------------------------------------------------
Type: wchar_t
Is integer: true
Is signed: true
Number of digits: 31
Number of digits 10: 9
Max Number of digits 10: 0
Min: -2147483648
Lowest: -2147483648
Max: 2147483647
Size in bytes: 4
Size in bits: 32
Numeric limits for type: int8_t
------------------------------------------------------------
Type: int8_t
Is integer: true
Is signed: true
Number of digits: 7
Number of digits 10: 2
Max Number of digits 10: 0
Min: -128
Lowest: -128
Max: 127
Size in bytes: 1
Size in bits: 8
Numeric limits for type: uint8_t
------------------------------------------------------------
Type: uint8_t
Is integer: true
Is signed: false
Number of digits: 8
Number of digits 10: 2
Max Number of digits 10: 0
Min: 0
Lowest: 0
Max: 255
Size in bytes: 1
Size in bits: 8
Numeric limits for type: int16_t
------------------------------------------------------------
Type: int16_t
Is integer: true
Is signed: true
Number of digits: 15
Number of digits 10: 4
Max Number of digits 10: 0
Min: -32768
Lowest: -32768
Max: 32767
Size in bytes: 2
Size in bits: 16
Numeric limits for type: uint16_t
------------------------------------------------------------
Type: uint16_t
Is integer: true
Is signed: false
Number of digits: 16
Number of digits 10: 4
Max Number of digits 10: 0
Min: 0
Lowest: 0
Max: 65535
Size in bytes: 2
Size in bits: 16
Numeric limits for type: int32_t
------------------------------------------------------------
Type: int32_t
Is integer: true
Is signed: true
Number of digits: 31
Number of digits 10: 9
Max Number of digits 10: 0
Min: -2147483648
Lowest: -2147483648
Max: 2147483647
Size in bytes: 4
Size in bits: 32
Numeric limits for type: uint32_t
------------------------------------------------------------
Type: uint32_t
Is integer: true
Is signed: false
Number of digits: 32
Number of digits 10: 9
Max Number of digits 10: 0
Min: 0
Lowest: 0
Max: 4294967295
Size in bytes: 4
Size in bits: 32
Numeric limits for type: int64_t
------------------------------------------------------------
Type: int64_t
Is integer: true
Is signed: true
Number of digits: 63
Number of digits 10: 18
Max Number of digits 10: 0
Min: -9223372036854775808
Lowest: -9223372036854775808
Max: 9223372036854775807
Size in bytes: 8
Size in bits: 64
Numeric limits for type: uint64_t
------------------------------------------------------------
Type: uint64_t
Is integer: true
Is signed: false
Number of digits: 64
Number of digits 10: 19
Max Number of digits 10: 0
Min: 0
Lowest: 0
Max: 18446744073709551615
Size in bytes: 8
Size in bits: 64
Numeric limits for type: short
------------------------------------------------------------
Type: short
Is integer: true
Is signed: true
Number of digits: 15
Number of digits 10: 4
Max Number of digits 10: 0
Min: -32768
Lowest: -32768
Max: 32767
Size in bytes: 2
Size in bits: 16
Numeric limits for type: unsigned short
------------------------------------------------------------
Type: unsigned short
Is integer: true
Is signed: false
Number of digits: 16
Number of digits 10: 4
Max Number of digits 10: 0
Min: 0
Lowest: 0
Max: 65535
Size in bytes: 2
Size in bits: 16
Numeric limits for type: int
------------------------------------------------------------
Type: int
Is integer: true
Is signed: true
Number of digits: 31
Number of digits 10: 9
Max Number of digits 10: 0
Min: -2147483648
Lowest: -2147483648
Max: 2147483647
Size in bytes: 4
Size in bits: 32
Numeric limits for type: unsigned int
------------------------------------------------------------
Type: unsigned int
Is integer: true
Is signed: false
Number of digits: 32
Number of digits 10: 9
Max Number of digits 10: 0
Min: 0
Lowest: 0
Max: 4294967295
Size in bytes: 4
Size in bits: 32
Numeric limits for type: long
------------------------------------------------------------
Type: long
Is integer: true
Is signed: true
Number of digits: 63
Number of digits 10: 18
Max Number of digits 10: 0
Min: -9223372036854775808
Lowest: -9223372036854775808
Max: 9223372036854775807
Size in bytes: 8
Size in bits: 64
Numeric limits for type: unsigned long
------------------------------------------------------------
Type: unsigned long
Is integer: true
Is signed: false
Number of digits: 64
Number of digits 10: 19
Max Number of digits 10: 0
Min: 0
Lowest: 0
Max: 18446744073709551615
Size in bytes: 8
Size in bits: 64
Numeric limits for type: long long
------------------------------------------------------------
Type: long long
Is integer: true
Is signed: true
Number of digits: 63
Number of digits 10: 18
Max Number of digits 10: 0
Min: -9223372036854775808
Lowest: -9223372036854775808
Max: 9223372036854775807
Size in bytes: 8
Size in bits: 64
Numeric limits for type: unsigned long long
------------------------------------------------------------
Type: unsigned long long
Is integer: true
Is signed: false
Number of digits: 64
Number of digits 10: 19
Max Number of digits 10: 0
Min: 0
Lowest: 0
Max: 18446744073709551615
Size in bytes: 8
Size in bits: 64
Numeric limits for type: float
------------------------------------------------------------
Type: float
Is integer: false
Is signed: true
Number of digits: 24
Number of digits 10: 6
Max Number of digits 10: 9
Min: 1.17549e-38
Lowest: -3.40282e+38
Max: 3.40282e+38
Size in bytes: 4
Size in bits: 32
Epsilon: 1.19209e-07
Min exponent: -37
Max exponent: 38
Numeric limits for type: double
------------------------------------------------------------
Type: double
Is integer: false
Is signed: true
Number of digits: 53
Number of digits 10: 15
Max Number of digits 10: 17
Min: 2.22507e-308
Lowest: -1.79769e+308
Max: 1.79769e+308
Size in bytes: 8
Size in bits: 64
Epsilon: 2.22045e-16
Min exponent: -307
Max exponent: 308
Numeric limits for type: long double
------------------------------------------------------------
Type: long double
Is integer: false
Is signed: true
Number of digits: 64
Number of digits 10: 18
Max Number of digits 10: 21
Min: 3.3621e-4932
Lowest: -1.18973e+4932
Max: 1.18973e+4932
Size in bytes: 16
Size in bits: 128
Epsilon: 1.0842e-19
Min exponent: -4931
Max exponent: 4932
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