1.c

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define max 100

struct Stack {
	char* origin;
	int count;
	int top;
	unsigned capacity;
} Stack;

struct Stack* createStack(unsigned cp){
	struct Stack* stack = (struct Stack*)malloc(sizeof(struct Stack));
	stack->capacity = cp;
	stack->top = -1;
	stack->origin = (char*)malloc(stack->capacity * sizeof(char));
	return stack;
}

int isFull(struct Stack* stack)
{
    return stack->top == stack->capacity - 1;
}

int isEmpty(struct Stack* stack)
{
    return stack->top == -1;
}

void push(struct Stack* stack, char item)
{
    if (isFull(stack))
        return;
    stack->origin[++stack->top] = item;
}


void print(struct Stack* stack){
	printf("%s\n", stack->origin);
}

char pop(struct Stack* stack)
{
    if (isEmpty(stack))
        return INT_MIN;
    stack->origin[stack->top] = '\0';
    stack->top--;
}


int main(){
	struct Stack* stack = createStack(1000);
	char str[max];
	char* check;
	char* cmp="*";
	fgets(str, max, stdin);
	int popping = 0;
	
	for ( check=&str[0]; *check != '\0'; check++ )
    {
    	int i1 = *cmp;
    	int i2 = *check;
    	if(i1 == i2){
			pop(stack);
			if(popping == 1){
				print(stack);
			}
			popping = 1;
		}else{
			push(stack, *check);
		}
	}
	

//	puts(str);
//	printf("%d", len);
}

3.c

#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define max 100

struct Stack {
	char* origin;
	int count;
	int top;
	unsigned capacity;
} Stack;

struct Stack* createStack(unsigned cp){
	struct Stack* stack = (struct Stack*)malloc(sizeof(struct Stack));
	stack->capacity = cp;
	stack->top = -1;
	stack->origin = (char*)malloc(stack->capacity * sizeof(char));
	return stack;
}

int isFull(struct Stack* stack)
{
    return stack->top == stack->capacity - 1;
}

int isEmpty(struct Stack* stack)
{
    return stack->top == -1;
}

void push(struct Stack* stack, char item)
{
    if (isFull(stack))
        return;
    stack->origin[++stack->top] = item;
}


void print(struct Stack* stack){
	printf("%s\n", stack->origin);
}

char pop(struct Stack* stack)
{
    if (isEmpty(stack))
        return INT_MIN;
    return stack->origin[stack->top--];
}


int main(){
	struct Stack* stack = createStack(1000);
	char str[max];
	char res[max];
	char* check;
	char* cmp="*";
	fgets(str, max, stdin);
	int popping = 0;
	
	int len = strlen(str), i;
	
	for ( check=&str[0]; *check != '\0'; check++ )
    {
		push(stack, *check);
	}
	for ( i = 0; i < len; i++ )
    {
		res[i] = pop(stack);
	}
	
	printf("%s\n", res);
	
}