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c++visual-studiointellisenselong-double

Long double and Intellisense in Visual Studio

As you know long double is identical to double in Visual Studio, unfortunately. However the intellisense feature shows a different story. For example check out the following code;

#include <iostream>
#include <iomanip>

using namespace std;

int main()

{
    cout << "Size of       float: " << sizeof(float)  << endl
         << "Size of      double: " << sizeof(double) << endl
         << "Size of long double: " << sizeof(long double)  << endl;


    cout << endl << setprecision(30) <<
        "      float: " << 125.6f << endl << 
        "     double: " << 125.6  << endl <<
        "long double: " << 125.6L;

    return 0;
}

Output is

Size of       float: 4
Size of      double: 8
Size of long double: 8

      float: 125.59999847412109375
     double: 125.599999999999994315658113919
long double: 125.599999999999994315658113919

But if you hover your mouse over 125.6L and 125.6, you see a difference in precision; double precision

long double precision

Although long double and double are identical in Visual Studio, what is the reason for the difference?

Solution

  • It appears that it's just the display that's different. The numeric section of the display seems to have a character limit and the character L causes the numeric section to round in some cases and even truncated.