Please write the function in C

Stack implementations you can use.

#include #include

#include "stack.h"

// creates a new stack stack_t* stack_create() { stack_t* s = (stack_t*) malloc(sizeof(stack_t)); s->top = NULL; return s; }

// pushes a given item to the stack // Pre condition: stack is not empty void stack_push(stack_t* s, void* item) { node_t* newTop = (node_t*) malloc(sizeof(node_t)); newTop->data = item; newTop->next = s->top; s->top = newTop; }

// pops the top element from the stack // Pre condition: stack is not empty void* stack_pop(stack_t* s) { void* ret = s->top->data; node_t* prevTop = s->top; s->top = prevTop->next; free(prevTop); return ret; }

// returns 1 if the stack is empty, and returns 0 otherwise int stack_is_empty(stack_t* s) { return (s->top == NULL); }

void stack_free(stack_t* s) { while (s->top) { node_t* prevTop = s->top; s->top = prevTop->next; free(prevTop); } free(s); }

Write a function that gets an array of tokens representing an arithmetic expression in the prefix notation, and computes the evaluation of the expression. Use the stack evaluation discussed in class. int prefix eval tokens (char** prefix expr, int n tokens) Examples On input ["+", "5", "-", "7", "2"] the function will return 10. This is because the expression is: ( 5 + ( 7-2 ) ) = 10. You may assume that all intermediate values in the computation are between 0 and *You may assume that the results of all division operations are integers. * You may use the stack implementation given in the assignment. The data in stack is of type void*. Use casting if necessary. Write a function that gets an array of tokens representing an arithmetic expression in the prefix notation, and computes the evaluation of the expression. Use the stack evaluation discussed in class. int prefix eval tokens (char** prefix expr, int n tokens) Examples On input ["+", "5", "-", "7", "2"] the function will return 10. This is because the expression is: ( 5 + ( 7-2 ) ) = 10. You may assume that all intermediate values in the computation are between 0 and *You may assume that the results of all division operations are integers. * You may use the stack implementation given in the assignment. The data in stack is of type void*. Use casting if necessary