strstr, wcsstr, _mbsstr, _mbsstr_l

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12/18/2017

The latest version of this topic can be found at strstr, wcsstr, _mbsstr, _mbsstr_l.

Returns a pointer to the first occurrence of a search string in a string.

Important

_mbsstr and _mbsstr_l cannot be used in applications that execute in the Windows Runtime. For more information, see CRT functions not supported with /ZW.

Syntax

char *strstr(  
   const char *str,  
   const char *strSearch   
); // C only  
char *strstr(  
   char *str,  
   const char *strSearch   
); // C++ only  
const char *strstr(  
   const char *str,  
   const char *strSearch   
); // C++ only  
wchar_t *wcsstr(  
   const wchar_t *str,  
   const wchar_t *strSearch   
); // C only  
wchar_t *wcsstr(  
   wchar_t *str,  
   const wchar_t *strSearch   
); // C++ only  
const wchar_t *wcsstr(  
   const wchar_t *str,  
   const wchar_t *strSearch   
); // C++ only  
unsigned char *_mbsstr(  
   const unsigned char *str,  
   const unsigned char *strSearch   
); // C only  
unsigned char *_mbsstr(  
   unsigned char *str,  
   const unsigned char *strSearch   
); // C++ only  
const unsigned char *_mbsstr(  
   const unsigned char *str,  
   const unsigned char *strSearch   
); // C++ only  
unsigned char *_mbsstr_l(  
   const unsigned char *str,  
   const unsigned char *strSearch,  
   _locale_t locale  
); // C only  
unsigned char *_mbsstr_l(  
   unsigned char *str,  
   const unsigned char *strSearch,  
   _locale_t locale  
); // C++ only  
const unsigned char *_mbsstr_l(  
   const unsigned char *str,  
   const unsigned char *strSearch,  
   _locale_t locale  
); // C++ only

Parameters

str
Null-terminated string to search.

strSearch
Null-terminated string to search for.

locale
Locale to use.

Return Value

Returns a pointer to the first occurrence of strSearch in str, or NULL if strSearch does not appear in str. If strSearch points to a string of zero length, the function returns str.

Remarks

The strstr function returns a pointer to the first occurrence of strSearch in str. The search does not include terminating null characters. wcsstr is the wide-character version of strstr and _mbsstr is the multibyte-character version. The arguments and return value of wcsstr are wide-character strings; those of _mbsstr are multibyte-character strings. _mbsstr validates its parameters. If str or strSearch is NULL, the invalid parameter handler is invoked, as described in Parameter Validation . If execution is allowed to continue, _mbsstr sets errno to EINVAL and returns 0. strstr and wcsstr do not validate their parameters. These three functions behave identically otherwise.

Important

These functions might incur a threat from a buffer overrun problem. Buffer overrun problems can be used to attack a system because they can allow the execution of arbitrary code, which can cause an unwarranted elevation of privilege. For more information, see Avoiding Buffer Overruns.

In C, these functions take a const pointer for the first argument. In C++, two overloads are available. The overload that takes a pointer to const returns a pointer to const; the version that takes a pointer to non-const returns a pointer to non-const. The macro _CONST_CORRECT_OVERLOADS is defined if both the const and non-const versions of these functions are available. If you require the non-const behavior for both C++ overloads, define the symbol _CONST_RETURN.

The output value is affected by the locale-category setting of LC_CTYPE; for more information, see setlocale, _wsetlocale. The versions of these functions that do not have the _l suffix use the current locale for this locale-dependent behavior; the versions that have the _l suffix are identical except that they instead use the locale parameter that's passed in. For more information, see Locale.

Generic-Text Routine Mappings

TCHAR.H routine	_UNICODE & _MBCS not defined	_MBCS defined	_UNICODE defined
`_tcsstr`	`strstr`	`_mbsstr`	`wcsstr`
n/a	n/a	`_mbsstr_l`	n/a

Requirements

Routine	Required header
`strstr`	<string.h>
`wcsstr`	<string.h> or <wchar.h>
`_mbsstr`, `_mbsstr_l`	<mbstring.h>

For more information about compatibility, see Compatibility.

Example

  
      // crt_strstr.c  
  
#include <string.h>  
#include <stdio.h>  
  
char str[] =    "lazy";  
char string[] = "The quick brown dog jumps over the lazy fox";  
char fmt1[] =   "         1         2         3         4         5";  
char fmt2[] =   "12345678901234567890123456789012345678901234567890";  
  
int main( void )  
{  
   char *pdest;  
   int  result;  
   printf( "String to be searched:\n   %s\n", string );  
   printf( "   %s\n   %s\n\n", fmt1, fmt2 );  
   pdest = strstr( string, str );  
   result = (int)(pdest - string + 1);  
   if ( pdest != NULL )  
      printf( "%s found at position %d\n", str, result );  
   else  
      printf( "%s not found\n", str );  
}

String to be searched:  
   The quick brown dog jumps over the lazy fox  
            1         2         3         4         5  
   12345678901234567890123456789012345678901234567890  
  
lazy found at position 36

.NET Framework Equivalent

System::String::IndexOf

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