strstr
From cppreference.com
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Defined in header
<string.h>
|
||
|
char
*
strstr
(
const
char
*
str,
const
char
*
substr
)
;
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(1) | |
|
/*QChar*/
*
strstr
(
/*QChar*/
*
str,
const
char
*
substr
)
;
|
(2) | (since C23) |
1)
Finds the first occurrence of the null-terminated byte string pointed to by
substr
in the null-terminated byte string pointed to by
str
. The terminating null characters are not compared.
2)
Type-generic function equivalent to
(1)
. Let
T
be an unqualified character object type.
-
-
If
stris of type const T * , the return type is const char * . -
Otherwise, if
stris of type T * , the return type is char * . - Otherwise, the behavior is undefined.
-
If
The behavior is undefined if either str or substr is not a pointer to a null-terminated byte string.
Parameters
| str | - | pointer to the null-terminated byte string to examine |
| substr | - | pointer to the null-terminated byte string to search for |
Return value
Pointer to the first character of the found substring in str , or a null pointer if such substring is not found. If substr points to an empty string, str is returned.
Example
Run this code
#include <stdio.h> #include <string.h> void find_str(char const* str, char const* substr) { char const* pos = strstr(str, substr); if (pos) printf( "Found the string [%s] in [%s] at position %td\n", substr, str, pos - str ); else printf( "The string [%s] was not found in [%s]\n", substr, str ); } int main(void) { char const* str = "one two three"; find_str(str, "two"); find_str(str, ""); find_str(str, "nine"); find_str(str, "n"); return 0; }
Output:
Found the string [two] in [one two three] at position 4 Found the string [] in [one two three] at position 0 The string [nine] was not found in [one two three] Found the string [n] in [one two three] at position 1
References
- C23 standard (ISO/IEC 9899:2024):
-
- 7.24.5.7 The strstr function (p: TBD)
- C17 standard (ISO/IEC 9899:2018):
-
- 7.24.5.7 The strstr function (p: 269)
- C11 standard (ISO/IEC 9899:2011):
-
- 7.24.5.7 The strstr function (p: 369)
- C99 standard (ISO/IEC 9899:1999):
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- 7.21.5.7 The strstr function (p: 332)
- C89/C90 standard (ISO/IEC 9899:1990):
-
- 4.11.5.7 The strstr function
See also
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finds the first occurrence of a character
(function) |
|
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finds the last occurrence of a character
(function) |
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C++ documentation
for
strstr
|
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