Send SSH-Password over C-Program

Hello @all!
I'd like to start a ssh-connection over a c-program. I've tried it with "pope". It looks like that:
//CODE
#include <iostream>
#include <string>
using namespace std;

int main()
{

 FILE *write_fp;
 char password[50];
 char command[50];
 sprintf(password, "thats_the_ssh_password");
 sprintf(command, "date");
 write_fp = popen("ssh -l root server", "w");
 fwrite(password, sizeof(char), strlen(password), write_fp);
 fwrite(command, sizeof(char), strlen(command), write_fp);
 pclose(write_fp);
}
//CODE
You see i try to:
- start "ssh -l root server"
- send the password to the "root@server's password: " prompt
- send a command ("date") over SSH to the server.

I've found out that SSH doesn't expect the password over the "normal-channel".
Does anybody know if there is the possibility to insert the password into the "ssh -l root server"-command?
That would solve the problem...

Thank you!
Best regards,
Mike