implement multiple pipes in c - operating-system

Question

I'm trying to implement multiple pipes in c++. Namely, I want to write a program to simulate the execution of, for example, ls -l | head -n 10 | wc -l.
The code works all fine. But after all the commands are executed correctly, I need to hit enter to return to the command line. I guess I have to "wait()" somewhere
Here is the code I'm having now.
using namespace std;
#include <stdio.h>
#include <iostream>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
int main(){
int pid;
int fd[4];
pipe(fd + 0); // pipe between the 1st and 2nd command
pipe(fd + 2); // pipe between the 2nd and 3rd command
for( int i = 0; i < 3; i++){ // 3 commands
pid = fork();
if(pid == 0){// child process
if( i == 0 ){// first command
char *arg[10];
arg[0] = "ls";
arg[1] = NULL;
close(fd[0]);
dup2(fd[1], 1);
execvp(arg[0], arg);
}
else if( i == 1){// second command
char *arg[10];
arg[0] = "head";
arg[1] = "-n1";
arg[2] = NULL;
dup2(fd[0], 0);
dup2(fd[3], 1);
execvp(arg[0], arg);
}
else if( i== 2){// third command
char *arg[10];
arg[0] = "wc";
arg[1] = "-l";
arg[2] = NULL;
close(fd[3]);
dup2(fd[2], 0);
execvp(arg[0], arg);
}
}
else{// parent
}
}
}
I think I have gone thru all posts similar to mine, but still can't figure this out.
Can anyone help?