C++ <cmath> - double_t Type
The C++ <cmath> double_t type is an alias of one of the fundamental floating-point types at least as wide as double. It is the type used by the implementation to evaluate values of type double, as determined by FLT_EVAL_METHOD.
| FLT_EVAL_METHOD | float_t | double_t |
|---|---|---|
| 0 | float | double |
| 1 | double | double |
| 2 | long double | long double |
| other | implementation-defined | implementation-defined |
In the <cmath> header file, it is defined as follows:
typedef /* implementation-defined */ double_t;
Example:
The example below shows the usage of double_t type.
#include <iostream>
#include <cmath>
#include <cfloat>
using namespace std;
int main (){
cout<<"FLT_EVAL_METHOD: "<<FLT_EVAL_METHOD<<"\n";
cout<<"sizeof(float_t): "<<sizeof(float_t)<<"\n";
cout<<"sizeof(double_t): "<<sizeof(double_t)<<"\n";
cout<<"sizeof(float): "<<sizeof(float)<<"\n";
cout<<"sizeof(double): "<<sizeof(double)<<"\n";
cout<<"sizeof(long double): "<<sizeof(long double)<<"\n";
return 0;
}
The output of the above code will be:
FLT_EVAL_METHOD: 0 sizeof(float_t): 4 sizeof(double_t): 8 sizeof(float): 4 sizeof(double): 8 sizeof(long double): 16
❮ C++ <cmath> Library
