printf() Default Floating-Point Precision Is 6 Decimals

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, and 6.0ax
      - Microsoft C for OS/2, versions 5.1, 6.0, and 6.0a
      - Microsoft C/C++ for MS-DOS, version 7.0
      - Microsoft Visual C++ for Windows, versions 1.0 and 1.5
      - Microsoft Visual C++ 32-bit Edition, versions 1.0, 2.0 and 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);
   }

   1.234568e+000
   1.234568e+000

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