printf() Default Floating-Point Precision Is 6 Decimals (29557)

The information in this article applies to:

The C Run-Time (CRT), when used with:
- Microsoft C for MS-DOS 5.1
- Microsoft C for MS-DOS 6.0
- Microsoft C for MS-DOS 6.0a
- Microsoft C for MS-DOS 6.0ax
- Microsoft C for OS/2 5.1
- Microsoft C for OS/2 6.0
- Microsoft C for OS/2 6.0a
- Microsoft C/C++ for MS-DOS 7.0
- Microsoft Visual C++ 1.0
- Microsoft Visual C++, 32-bit Learning Edition 4.0
- Microsoft Visual C++, 32-bit Professional Edition 2.0
- Microsoft Visual C++, 32-bit Professional Edition 4.0

This article was previously published under Q29557

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);

Modification Type:	Major	Last Reviewed:	12/11/2003
Keywords:	kbCRT KB29557