`_set_output_format`

مقالة
10/26/2022

Customizes output formats used by formatted I/O functions.

Important

This function is obsolete. Beginning in Visual Studio 2015, it is not available in the CRT.

Syntax

unsigned int _set_output_format(
   unsigned int format
);

Parameters

format
[in] An value representing the format to use.

Return value

The previous output format.

Remarks

_set_output_format is used to configure the output of formatted I/O functions such as printf_s. The only formatting convention that can be changed by this function is the number of digits displayed in exponents in the output of floating point numbers.

By default, the output of floating point numbers by functions such as printf_s, wprintf_s, and related functions in the Visual C++ Standard C library prints three digits for the exponent, even if three digits aren't required to represent the value of the exponent. Zeroes are used to pad the value to three digits. _set_output_format allows you to change this behavior so that only two digits are printed in the exponent unless a third digit is required by the size of the exponent.

To enable two-digit exponents, call this function with the parameter _TWO_DIGIT_EXPONENT, as shown in the example. To disable two digit exponents, call this function with an argument of 0.

Requirements

Routine	Required header
`_set_output_format`	<stdio.h>

For more compatibility information, see Compatibility in the Introduction.

Example

// crt_set_output_format.c
#include <stdio.h>

void printvalues(double x, double y)
{
   printf_s("%11.4e %11.4e\n", x, y);
   printf_s("%11.4E %11.4E\n", x, y);
   printf_s("%11.4g %11.4g\n", x, y);
   printf_s("%11.4G %11.4G\n", x, y);
}

int main()
{
   double x = 1.211E-5;
   double y = 2.3056E-112;
   unsigned int old_exponent_format;

   // Use the default format
   printvalues(x, y);

   // Enable two-digit exponent format
   old_exponent_format = _set_output_format(_TWO_DIGIT_EXPONENT);

   printvalues(x, y);

   // Disable two-digit exponent format
   _set_output_format( old_exponent_format );

   printvalues(x, y);
}

1.2110e-005 2.3056e-112
1.2110E-005 2.3056E-112
1.211e-005  2.306e-112
1.211E-005  2.306E-112
1.2110e-05 2.3056e-112
1.2110E-05 2.3056E-112
  1.211e-05  2.306e-112
  1.211E-05  2.306E-112
1.2110e-005 2.3056e-112
1.2110E-005 2.3056E-112
1.211e-005  2.306e-112
1.211E-005  2.306E-112

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