strstr

 

C

Language

Standard Library

Type support

Dynamic memory management

Error handling

Program utilities

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Thread support (C11)

Atomic operations (C11)

 

Strings library

Byte strings

Multibyte strings

Wide strings

 

Null-terminated byte strings

Functions
Character manipulation
isalnum isalpha islower isupper isdigit isxdigit isblank (C++11)	iscntrl isgraph isspace isprint ispunct tolower toupper
Conversions to numeric formats
atof atoi atol atoll strtol strtoll	strtoul strtoull strtof strtod strtold
String manipulation
strcpy
strncpy
strcat
strncat
strxfrm
String examination
strlen strcmp strncmp strcoll strchr strrchr	strspn strcspn strpbrk strstr strtok
Memory manipulation
memchr
memcmp
memset
memcpy
memmove
Miscellaneous
strerror

 

Defined in header <string.h>
char *strstr( const char* str, const char* substr );

Finds the first occurrence of the byte string substr in the byte string pointed to by str.

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

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: %d\n", substr, str, pos - str);
    } else {
        printf("the string '%s' was not found in '%s'\n", substr, str);
    }
}
 
int main(int argc, char* argv[]) 
{
    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

See also

strchr	finds the first occurrence of a character (function)
strrchr	finds the last occurrence of a character (function)