Postfix

//srishti1302
#include<stdio.h>
#define MAX_STACK_SIZE 100
typedef enum{

    lparen,rparen,plus,minus,times,divide,mod,eos,operand
}precedence;
precedence stacks[MAX_STACK_SIZE];
char exprs[MAX_STACK_SIZE];
static int isp[]={0,19,12,12,13,13,13,0};
static int icp[]={20,19,12,12,13,13,13,0};

precedence get_tokens(char *symbols,int *ns){
    *symbols=exprs[(*ns)++];

    switch(*symbols)
    {
        case '(':return lparen;

        case ')':return rparen;

        case '+':return plus;

        case '-':return minus;

        case '%':return mod;
        case '/':return divide;

        case '\0':return eos;
        case '*':return times;

        default: return operand;

    }
}


void addp(int *tops,precedence xs){
  // printf("\n in add func top=%d x=%x",%d);
    stacks[++*tops]=xs;

}


int delp(int *tops){
//    stack[]
    return stacks[(*tops)--];
}

void print_token(precedence X){
    switch(X){
        case plus:  printf("+");
                    break;
        case minus:  printf("-");
                    break;
        case times:  printf("*");
                    break;
        case divide:  printf("/");
                    break;
        case mod:  printf("%%");
                    break;
        case eos :break;
    }
}


void postfix(){

    char symbols;
    precedence tokens;
    int ns=0;
    int tops=0;
    stacks[0]=eos;
    for(tokens=get_tokens(&symbols,&ns); tokens!=eos; tokens=get_tokens(&symbols,&ns))
    {
        if(tokens==operand)
            printf("%c",symbols);
        else if(tokens==rparen){
            while(stacks[tops]!=lparen)
                print_token(delp(&tops));
            delp(&tops);
        }
        else{

            while(isp[stacks[tops]]>=icp[tokens])

                print_token(delp(&tops));


            addp(&tops,tokens);
        }

    }

    while((tokens=delp(&tops))!=eos)
        print_token(tokens);

    printf("\n");

}
int main(){

    printf("Enter infix expression to be converted to postfix");
    gets(exprs);

    postfix();
    return 0;
}