Question

Please code in C


/* Implements functions that operate on Stack
   1. PUSH
   2. POP 
   3. isEmpty
   4. PEEK
   5. Size
  */

#include <stdio.h>

#define CAPACITY 1000

//Two stacks .. for each stack we need
// 1. An Array that can hold capacity of elements
// 2. A top initialzied to -1 (signifying that the stak is empty at the start)
//NOTE : THESE STACKS ARE OF TYPE CHAR :(  ... so you need to FIX IT!!!! to int and every function as well :((

char stack1[CAPACITY];
char stack2[CAPACITY];

int top1 = -1;
int top2 = -1;

int push(char stack[], int top, char data){
        if(*top<CAPACITY-1){
                *top += 1;
                stack[*top] = data;
                return 1;
        }
        return 0;
}

char pop(char stack[], int* top){
        char c;
        if(*top > -1){
                c = stack[*top];
                *top -=1;
        }
        return c;
} 


char peek(char stack[], int* top){
        char c = 0;
        if(*top > -1){
                c = stack[*top];
        }
        return c;
}

int isEmpty(char stack[],int* top){
        if (*top == -1)
                return 1;
        return 0;
}

int size(char stack[],int* top){
        return *top+1;
}



int main(){
        //YOUR CODE HERE for REVESE POLISH NOTATION CALCULATION!
}

Answer 1

Here's a C Code for the question:

int stack1[CAPACITY];
int stack2[CAPACITY];

int top1 = -1;
int top2 = -1;

int push(int stack[], int top, int data){
        if(*top<CAPACITY-1){
                *top += 1;
                stack[*top] = data;
                return 1;
        }
        return 0;
}

int pop(int stack[], int* top){
        int c;
        if(*top > -1){
                c = stack[*top];
                *top -=1;
        }
        return c;
} 


int peek(int stack[], int* top){
        int c = 0;
        if(*top > -1){
                c = stack[*top];
        }
        return c;
}

int isEmpty(int stack[],int* top){
        if (*top == -1)
                return 1;
        return 0;
}

int size(int stack[],int* top){
        return *top+1;
}



int evaluateReversePolish(char *exp){

        for (i = 0; exp[i]; i++) 
        { 
        // If the scanned character is an operand (number here), 
        // push it to the stack. 
                if (exp[i]>='0'&&exp[i]<='9') 
                    push(stack1, exp[i] - '0'); 

                // If the scanned character is an operator, pop two 
                // elements from stack apply the operator 
                else
                { 
                    int val1 = pop(stack1); 
                    int val2 = pop(stack1); 
                    switch (exp[i]) 
                    { 
                            case '+': push(stack1, val2 + val1); break; 
                            case '-': push(stack1, val2 - val1); break; 
                            case '*': push(stack1, val2 * val1); break; 
                            case '/': push(stack1, val2/val1); break; 
                    } 
                } 
        } 
        return pop(stack1); 
}