How can I use “s.find” in c++

In C, you can use the strstr() function to find the first occurrence of a substring within a string. The function takes two arguments, the string to search in and the substring to search for. It returns a pointer to the first occurrence of the substring, or NULL if the substring is not found. Here is an example:

#include <stdio.h>
#include <string.h>

int main() {
    char str[] = "Hello, world!";
    char substr[] = "world";
    char *ptr = strstr(str, substr);
    if (ptr != NULL) {
        printf("Substring found at position %ld\n", ptr - str);
    } else {
        printf("Substring not found\n");
    }
    return 0;
}

Output:

Substring found at position 7

In this example, we are searching for the substring "world" within the string "Hello, world!". The strstr() function returns a pointer to the first occurrence of the substring, which we can use to calculate its position within the string. If the substring is not found, strstr() returns NULL.