Difference between revisions of "c/string/byte/strstr"
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− | {{c/title| strstr}} | + | {{c/title|strstr}} |
{{c/string/byte/navbar}} | {{c/string/byte/navbar}} | ||
− | {{ | + | {{dcl begin}} |
− | {{ | + | {{dcl header|string.h}} |
− | {{ | + | {{dcl|num=1| |
− | + | char* strstr( const char* str, const char* substr ); | |
}} | }} | ||
− | {{ | + | {{dcl|num=2|since=c23| |
− | + | /*QChar*/* strstr( /*QChar*/* str, const char* substr ); | |
}} | }} | ||
− | {{ | + | {{dcl end}} |
− | Finds the first occurrence of the byte string {{ | + | @1@Finds the first occurrence of the null-terminated byte string pointed to by {{c|substr}} in the null-terminated byte string pointed to by {{c|str}}. The terminating null characters are not compared. |
+ | @2@ {{dsc clang type generic fun|char|str}} | ||
+ | |||
+ | The behavior is undefined if either {{c|str}} or {{c|substr}} is not a pointer to a null-terminated byte string. | ||
===Parameters=== | ===Parameters=== | ||
− | {{ | + | {{par begin}} |
− | {{ | + | {{par|str|pointer to the null-terminated byte string to examine}} |
− | {{ | + | {{par|substr|pointer to the null-terminated byte string to search for}} |
− | {{ | + | {{par end}} |
===Return value=== | ===Return value=== | ||
− | Pointer to the first character of the found substring in {{ | + | Pointer to the first character of the found substring in {{c|str}}, or a null pointer if such substring is not found. If {{c|substr}} points to an empty string, {{c|str}} is returned. |
===Example=== | ===Example=== | ||
{{example | {{example | ||
− | + | |code= | |
− | + | ||
− | + | ||
#include <stdio.h> | #include <stdio.h> | ||
+ | #include <string.h> | ||
− | void find_str(char const* str, char const* substr) | + | void find_str(char const* str, char const* substr) |
{ | { | ||
− | char* pos = strstr(str, substr); | + | char const* pos = strstr(str, substr); |
− | if(pos) | + | if (pos) |
− | printf(" | + | printf( |
− | + | "Found the string [%s] in [%s] at position %td\n", | |
− | printf(" | + | substr, str, pos - str |
− | + | ); | |
+ | else | ||
+ | printf( | ||
+ | "The string [%s] was not found in [%s]\n", | ||
+ | substr, str | ||
+ | ); | ||
} | } | ||
− | int main( | + | int main(void) |
{ | { | ||
− | char* str = "one two three"; | + | char const* str = "one two three"; |
find_str(str, "two"); | find_str(str, "two"); | ||
find_str(str, ""); | find_str(str, ""); | ||
find_str(str, "nine"); | find_str(str, "nine"); | ||
find_str(str, "n"); | find_str(str, "n"); | ||
− | + | ||
return 0; | 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=== | ||
+ | {{ref std c23}} | ||
+ | {{ref std|section=7.24.5.7|title=The strstr function|p=TBD}} | ||
+ | {{ref std end}} | ||
+ | {{ref std c17}} | ||
+ | {{ref std|section=7.24.5.7|title=The strstr function|p=269}} | ||
+ | {{ref std end}} | ||
+ | {{ref std c11}} | ||
+ | {{ref std|section=7.24.5.7|title=The strstr function|p=369}} | ||
+ | {{ref std end}} | ||
+ | {{ref std c99}} | ||
+ | {{ref std|section=7.21.5.7|title=The strstr function|p=332}} | ||
+ | {{ref std end}} | ||
+ | {{ref std c89}} | ||
+ | {{ref std|section=4.11.5.7|title=The strstr function}} | ||
+ | {{ref std end}} | ||
===See also=== | ===See also=== | ||
− | {{ | + | {{dsc begin}} |
− | {{ | + | {{dsc inc|c/string/byte/dsc strchr}} |
− | {{ | + | {{dsc inc|c/string/byte/dsc strrchr}} |
− | {{ | + | {{dsc see cpp|cpp/string/byte/strstr}} |
− | {{ | + | {{dsc end}} |
+ | |||
+ | {{langlinks|ar|cs|de|es|fr|it|ja|ko|pl|pt|ru|tr|zh}} |
Latest revision as of 04:06, 5 October 2024
Defined in header <string.h>
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char* strstr( const char* str, const char* substr ); |
(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
str
is of type const T*, the return type is const char*. - Otherwise, if
str
is 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.
Contents |
[edit] Parameters
str | - | pointer to the null-terminated byte string to examine |
substr | - | pointer to the null-terminated byte string to search for |
[edit] 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.
[edit] 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
[edit] 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
[edit] See also
finds the first occurrence of a character (function) | |
finds the last occurrence of a character (function) | |
C++ documentation for strstr
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