Using C++ to read a file on a remote Linux-type server

I am building a small network of Raspberry Pi's using Raspian with samba file sharing. I want each to be able to read/write small text files to the others, to provide a very simple method of process co-ordination. I am a testing the method with one Pi with a single shared file and can read/write to it from an Ubuntu laptop, using its desktop file manager. I am trying to do the same programmatically:

#include<string>
#include<iostream>
#include<fstream>
using namespace std;

void read_file () {
    string line;
    
    ifstream myfile;
    myfile.open("\\\\192.168.1.78\\home\\pi\\new2.txt");
    if (myfile.is_open()){
        cout << "file is open" << endl;
            getline(myfile, line);
            cout<< line << endl;
    } else {
        perror("Error");
    }   
    myfile.close();
}

int main(){
    read_file();
}

The error message is 'No such file or directory'. I'm guessing this is either a permissions problem I've not seen (the remote file is shared as 777) or the way I'm referencing the server and folder. I've tried numerous combinations to no avail.

Any suggestions?