printf() Default Floating-Point Precision Is 6 Decimals

ID: Q29557

The information in this article applies to:

The C Run-Time (CRT), included with:
- Microsoft C for MS-DOS, versions 5.0, 5.1, 6.0, 6.0a, 6.0ax
- Microsoft C for OS/2, versions 5.1, 6.0, 6.0a
- Microsoft C/C++ for MS-DOS, version 7.0
- Microsoft Visual C++ for Windows, versions 1.0, 1.50
- Microsoft Visual C++ 32-bit Edition, versions 1.0, 2.0, 4.0

SUMMARY

By default, the printf() function displays a floating-point number to six digits of precision. This default also holds for double precision numbers.

To display additional digits of precision, specify a value for the precision field in the printf() format specification, as follows:

%[<flags>][<width>][.<precision>]<type>

MORE INFORMATION

The code example below demonstrates documented printf() behavior that may appear to be a problem with the function.


   #include <stdio.h>

   main()
   {
      double d = 1.2345678912;

      printf("%e\n", d);
      printf("%le\n", d);
   }

This code example produces the following output:


   1.234568e+000
   1.234568e+000

To display the value d to its full precision, modify the code example to use the following statement:


   printf("%.15le", d);

Additional query words: kbinf 1.00 1.50 2.00 5.10 6.00 6.00a 6.00ax 7.00

Keywords : kbCRT kbVC
Version : winnt:
Platform : winnt
Issue type :