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sscanf, swscanf

Visual Studio .NET 2003

Read formatted data from a string.

int sscanf(
   const char *buffer,
   const char *format [,
   argument ] ... 
);
int swscanf(
   const wchar_t *buffer,
   const wchar_t *format [,
   argument ] ... 
);

Parameters

buffer: Stored data
format: Format-control string. For more information, see Format Specifications.
argument: Optional arguments

Return Value

Each of these functions returns the number of fields successfully converted and assigned; the return value does not include fields that were read but not assigned. A return value of 0 indicates that no fields were assigned. The return value is EOF for an error or if the end of the string is reached before the first conversion.

Remarks

The sscanf function reads data from buffer into the location given by each argument. Every argument must be a pointer to a variable with a type that corresponds to a type specifier in format. The format argument controls the interpretation of the input fields and has the same form and function as the format argument for the scanf function. If copying takes place between strings that overlap, the behavior is undefined.

Security Note When reading a string with sscanf, always specify a width for the %s format (for example, "32%s" instead of "%s"); otherwise, improperly formatted input can easily cause a buffer overrun.

swscanf is a wide-character version of sscanf; the arguments to swscanf are wide-character strings. sscanf does not handle multibyte hexadecimal characters. swscanf does not handle Unicode fullwidth hexadecimal or "compatibility zone" characters. Otherwise, swscanf and sscanf behave identically.

Generic-Text Routine Mappings

TCHAR.H routine	_UNICODE & _MBCS not defined	_MBCS defined	_UNICODE defined
_stscanf	sscanf	sscanf	swscanf

Requirements

Routine	Required header	Compatibility
sscanf	<stdio.h>	ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP
swscanf	<stdio.h> or <wchar.h>	ANSI, Win 98, Win Me, Win NT, Win 2000, Win XP

For additional compatibility information, see Compatibility in the Introduction.

Libraries

All versions of the C run-time libraries.

Example

// crt_sscanf.c
/* This program uses sscanf to read data items
 * from a string named tokenstring, then displays them.
 */

#include <stdio.h>

int main( void )
{
   char  tokenstring[] = "15 12 14...";
   char  s[81];
   char  c;
   int   i;
   float fp;

   /* Input various data from tokenstring: */
   sscanf( tokenstring, "%80s", s ); // max 80 character string
   sscanf( tokenstring, "%c", &c );
   sscanf( tokenstring, "%d", &i );
   sscanf( tokenstring, "%f", &fp );

   /* Output the data read */
   printf( "String    = %s\n", s );
   printf( "Character = %c\n", c );
   printf( "Integer:  = %d\n", i );
   printf( "Real:     = %f\n", fp );
}

Output

String    = 15
Character = 1
Integer:  = 15
Real:     = 15.000000