strstr
From cppreference.com
Defined in header <string.h>
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char
* strstr(
const
char
* str, const
char
* substr )
;
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(1) | |
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/*QChar*/
* strstr(
/*QChar*/
* str, const
char
* substr )
;
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(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
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
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):
- 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
| 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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