strstr

Header: <string.h>

  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.

# Declarations

char* strstr( const char* str, const char* substr );

/*QChar*/* strstr( /*QChar*/* str, const char* substr );

(since C23)

# Parameters

# 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

#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;
}

# See also