Please help me to convert this C++ code to a C code. Thank you! !

#include<iostream>
using namespace std;
void line(int,int,int);
int main()
{int i;
do
{cout<<"How many rows? ";
cin>>i;
if(i<0)
    cout<<"must be nonnegative\n";
}while(i<0);
line(i,1,i);
system("pause");
return 0;
}
void line(int m,int n,int p)
{int i;
if(m>p)
     return;
for(i=0;i<m;i++)
    cout<<"*";
if(m>0)
    cout<<endl;
if(m==0||n==0)
   line(m+1,0,p);
else
    line(m-1,n,p);
}

---------------------------------

#include<iostream>
using namespace std;
void line2(int,int,int);
int main()
{int i;
do
{cout<<"How many rows? ";
cin>>i;
if(i<0)
    cout<<"must be nonnegative\n";
}while(i<0);
line2(1,1,i);
system("pause");
return 0;
}

void line2(int m,int n,int p)
{int i;
if(m<n)
     return;
for(i=0;i<m;i++)
    cout<<"*";
if(m>0)
    cout<<endl;
if(m==p||n==0)
   line2(m-1,0,p);
else
    line2(m+1,n,p);
}