Transform the Expression

4. Transform the Expression Problem code: ONP

#include<stdio.h>
#include<ctype.h>
char stack[1000];
int top;

void initialize_stack()
{
    top=-1;
}

char pop()
{
    return stack[top--];
}

void push(char x)
{
    stack[++top]=x;
}

int precedence(char op)
{
    if (op=='^')
        return 3;
    if((op=='*')||(op=='/'))
        return 2;
  
    else if ((op=='+')||(op=='-'))
        return 1;
}

int greater_or_equal( char op1 , char op2 )
{
    return(precedence(op1)>=precedence(op2));
}

int is_operator(char c)
{
    return (c=='*')||(c=='/')||(c=='+')||(c=='-' ||c=='^');
}

int main()
{
    int in;
    char c;
  
    in=0;
    initialize_stack();
    int t;
    scanf("%d\n",&t);
    while (t--)
    {
    while((c=getchar())!='\n')
    {
        if ( (isalpha(c)) ||(c=='.'))
        {
            printf("%c",c);
        }
           
         else if(is_operator(c))
         {
              while( (top!=-1) && (stack[top]!='(') && (greater_or_equal(stack[top],c)) )
                    printf("%c",pop());
                    
              push(c);
          }
                
         else if(c=='(')
             push(c);
                
          else if(c==')')
         { 
              while(stack[top]!='(')
                    printf("%c",pop());
                    top--;
          }
       
      }

    while(top!=-1)
        printf("%c",pop());
          printf("\n");
        }
}