strstr
Defined in header <string.h>
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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.
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 NULL
if no such substring is found. If substr
points to an empty string, str
is returned.
Example
#include <string.h>
#include <stdio.h>
void find_str(char const* str, char const* substr)
{
char* pos = strstr(str, substr);
if(pos) {
printf("found the string '%s' in '%s' at position: %ld\n", substr, str, pos - str);
} else {
printf("the string '%s' was not found in '%s'\n", substr, str);
}
}
int main(void)
{
char* 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
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) | |
finds the last occurrence of a character (function) |
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