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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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 a null pointer if such substring is not found. If substr points to an empty string, str is returned.
Example
Run this code
#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)