Need help soccer simulation - c++

Question

I need help with a winning condition and randomly placing teams against each other...i randomly selecting teams to play and i keep getting the same teams playing twice or playing itself and idk what to do
#include <iostream>
#include <ctime>
#include <fstream>
#include <string>
#include <cmath>
#include <stdlib.h>
#include <sstream>
using namespace std;
struct teams{//declaring a struct for the teams
string side;
int number;
int number1;
}teams1[16], points[16];
//void intro screen(){//function for the introduction screen
void fileData(){//function for reading the teams data file
ifstream input;
input.open("FootballTeam.txt",ios::in); //associate file
if(input.is_open()){//opening the file
for(int x=0; x<16; x++){//looping through the file
input>>teams1[x].side;//getting info from the file
cout<<teams1[x].side<<endl;//printing out the data from the file
}//end for
}//end if
}//end void
void play(){//function for playing the game
srand(time(NULL));
for(int x=0; x<=1; x++){//loop for random teams to play
for(int s=0; s<=7; s++){//loop for randoms goals value
x=rand() %16+1;//randomly selecting two teams
points[s].number=rand()%4+1;//randomly selecting goals
points[s].number1=rand()%7+3;//randomly selecting goals
cout<<teams1[x].side<<" :"<<points[s].number<<" vs "
<<teams1[s].side<<" :"<<points[s].number1<<endl<<endl;//printing out the teams and goals
//cout<<teams1<<" Won this match"<<endl;
}//end for
}//end for
}//end void
int main (){
cout<<"ROUND OF 16 Finalists!!!\n"<<endl;
fileData();
cout<<"\n";
system("PAUSE");
system("CLS");
play();
return 0;
}//end main

Answer 1

The rand() pseudo-random number generator uses its default seed if you don't call srand() before using rand(). To prevent rand() from using the default seed on every run of your program, and thereby always choosing the same pairs of teams, you should call srand() and pass in time(NULL), which I see you have done. Since your program will never run at the same time twice, rand() will output different numbers on each run.
However, note that you should only call srand() once. So you need to call it in main(), as soon as your program starts up. Right now you're calling srand() every time play() is invoked. The time intervals between each invocation of play() are probably very small. Thus, rand() ends up being seeded with virtually the same number every time, since the time differences are too small. This effectively starts rand() at the same point in its pseudo-random number sequence, which is why you see the same teams playing each other.
int main() {
srand(time(NULL));
// now you're free to use rand() for the rest of the program
// ...
}
See this reference for more information on srand().