Программа с меню

#include <iostream.h>
#include <iomanip.h>
#include <string.h>
 
struct avia {int n, k;
char name[10], surname[15];} a[12];
 
int menu_1(int);
void mesta(const struct avia a[]);
struct avia vvod(int n);
 
void main()
{
 
int m,r,t,s;
 
for(t=0;t<12;t++)
{
a[t].n = t+1;
a[t].k = 0;
}
 
while (m!=4) 
 
{
 
flush(cout);
 
cout<<"******************************"<<endl;
cout<<"1 - kolichestvo svobodnyh mest"<<endl;
cout<<"2 - perechen' svobodnyh mest"<<endl;
cout<<"3 - rezervirovanie mest"<<endl;
cout<<"4 - exit"<<endl;
cout<<"******************************"<<endl;
 
cin>>m;
 
switch(m)
{
case 1: flush(cout);cout<< menu_1(s)<<endl; break;
case 2: flush(cout);mesta(a); break;
case 3: flush(cout);cout<<"vvedite nomer mesta"<<endl; cin>>r; a[r-1] = vvod(r); break;
case 4: flush(cout);break;
default: flush(cout);break;
}
 
}
 
return;
}
 
int menu_1(int q) //perechen vsex mest
{ int i;
q=0;
for (i=0;i<12;i++)
if (a[i].k==0) q+=1;
return(q);}
 
// func vyvodit svobodnye mesta
//
void mesta(const struct avia a[]) 
{
int i;
 
for (i=0;i<12;i++)
{
if(a[i].k==0) 
cout<<a[i].n<<endl;
}
}
 
// rezervirovanie mesta
struct avia vvod(int n)
{
avia temp;
 
temp.n = n-1;
temp.k = 1;
cout<<"vvedite vashu familiu"<<endl;
cin>>temp.surname;
cout<<"vvedite vashe imya"<<endl;
cin>>temp.name;
 
return temp;}

char ShowMenu()
{
system("cls");
cout<<"******************************"<<endl;
cout<<"1 - kolichestvo svobodnyh mest"<<endl;
cout<<"2 - perechen' svobodnyh mest"<<endl;
cout<<"3 - rezervirovanie mest"<<endl;
cout<<"4 - exit"<<endl;
cout<<"******************************"<<endl;
int m;
cin>>m;
return m;
}
 
void main()
{
...
int option;
while ((option=ShowMenu())!=4)
{
switch(option)
 {
case 1: flush(cout);cout<< menu_1(s)<<endl; break;
case 2: flush(cout);mesta(a); break;
case 3: flush(cout);cout<<"vvedite nomer mesta"<<endl; cin>>r; a[r-1] = vvod(r); break;
case 4: flush(cout);break;
default: flush(cout);break;
 }
}