How can one find a substring of an entered string in C++? For example, I entered the line: “Hello World”, then I enter “llo” and if the first line in the input contains such a substring, then let it output true. This is something that needs to be created, but I don’t know how to search for a match in a string.

Answer 1, authority 100%

# include & lt; string & gt;

#include & lt; iostream & gt;

int main () {

  std :: string s = "Hello world";

  size_t pos = s.find ("ell");

  if (pos! = std :: string :: npos)

    std :: cout & lt; & lt; "Found at pos =" & lt; & lt; pos & lt; & lt; "\ n";

  else

    std :: cout & lt; & lt; "Not found \ n";

}


Answer 2, authority 55% 
man strstr 

Returns a pointer to the first occurrence of the search string in a string.