prefix to postfix

#include
#include
#include
char inf[240],post[40];
int top=0, st[20];
void postfix();
void infix();
char pop();
main()
{
clrscr();
cout<<"Infix to Postfix";
cout<<"\n Enter ninfix expression";
cin>>inf;
getch();
}
void postfix()
{
int i,j=0;
for(i=0,inf[i]!=0;i++)
{
switch(inf[i])
{
case'+';
while(st[top]>=1)
post[j++]pop();
push(1);
break;
case'-';
while(st[top]>=2)
post[j++]pop();
push(2);
break;
case'*';
while(st[top]>=3)
post[j++]pop();
push(3);
break;
case'/';
while(st[top]>=4)
post[j++]pop();
push(4);
break;
case'(';
push(0);
break;