what do i need to do to get this popen code to run :

#include

#include

#include

using namespace std;

int main(){

char s[100];

cout << "please enter a command";

cin >> s

FILE *fp = popen(s,"r");

const int BUFFER_SIZE = 100;

char buff[BUFFER_SIZE];

//cout << "Enter your command: ";

//cin >> buff;

while(fgets(buf, BUFFER_SIZE, fp)){

cout << buf

}

pclose(fp);

}

do{

char s[100];

cout << "please enter a command";

cin >> s

FILE *fp = popen(s,"r");

const int BUFFER_SIZE = 100;

char buff[BUFFER_SIZE];

//cout << "Enter your command: ";

//cin >> buff;

while(fgets(buf, BUFFER_SIZE,fp)){

cout << buf

3while(strcmp(s,"exit"))

}

}