/*  

*Copyright (c)2017, School of computer and control engineering, Yantai University

*All rights reservrd.           

*Author: Li Xinhao

*Completion time: December 14, 2017

*Version number: v1.0

*Problem Description: suppose three kinds of parentheses are allowed in an expression: parentheses, square brackets, and braces. Write an algorithm to determine whether the various left parentheses in the expression match the right parentheses.  
For example, input 2 + (3 + 4) * 2 + {[3]} - 8, output matching is correct; input 2 + (3 + 4 * [2) + {[3]} - 8, output matching is wrong.

1, Create a new project to create a header file based on the sequence stack database:

#ifndef SQSTACK_H_INCLUDED
#define SQSTACK_H_INCLUDED

#define MaxSize 100
typedef char ElemType;
typedef struct
{
    ElemType data[MaxSize];
    int top;                //Stack pointer
} SqStack;                  //Sequence stack type definition

void InitStack(SqStack *&s);    //Initialization stack
void DestroyStack(SqStack *&s);  //Destruction stack
bool StackEmpty(SqStack *s);     //Is the stack empty
int StackLength(SqStack *s);  //Return the number of elements in the stack -- stack length
bool Push(SqStack *&s,ElemType e); //Push
bool Pop(SqStack *&s,ElemType &e); //Stack out
bool GetTop(SqStack *s,ElemType &e); //Data element at the top of stack
void DispStack(SqStack *s);  //Output stack

#endif // SQSTACK_H_INCLUDED

2, Create the source file sqstack.cpp to define these functions:

#include <stdio.h>
#include <malloc.h>
#include "sqstack.h"

void InitStack(SqStack *&s)
{
    s=(SqStack *)malloc(sizeof(SqStack));
    s->top=-1;
}
void DestroyStack(SqStack *&s)
{
    free(s);
}
int StackLength(SqStack *s)  //Return the number of elements in the stack -- stack length
{
    return(s->top+1);
}
bool StackEmpty(SqStack *s)
{
    return(s->top==-1);
}
bool Push(SqStack *&s,ElemType e)
{
    if (s->top==MaxSize-1)    //Stack full, i.e. stack overflow
        return false;
    s->top++;
    s->data[s->top]=e;
    return true;
}
bool Pop(SqStack *&s,ElemType &e)
{
    if (s->top==-1)     //When the stack is empty, i.e. overflow under the stack
        return false;
    e=s->data[s->top];
    s->top--;
    return true;
}
bool GetTop(SqStack *s,ElemType &e)
{
    if (s->top==-1)         //When the stack is empty, i.e. overflow under the stack
        return false;
    e=s->data[s->top];
    return true;
}

void DispStack(SqStack *s)  //Output stack
{
    int i;
    for (i=s->top;i>=0;i--)
        printf("%c ",s->data[i]);
    printf("\n");
}

3, Set up the source file main.cpp to achieve the following functions:

#include <stdio.h>
#include "sqstack.h"
int main()
{
    char c;
    char st[50];
    int d=1, i;
    SqStack *s;
    InitStack(s);
    printf("Please enter an expression:");
    scanf("%s", st);
    for(i=0; st[i]!='\0'&&d; i++)
    {
        switch(st[i])
        {
        case'(':
        case'[':
        case'{':
            Push(s, st[i]);
            break;
        case')':
            Pop(s, c);
            if(c!='(') d=0;
            break;
        case']':
            Pop(s, c);
            if(c!='[') d=0;
            break;
        case'}':
            Pop(s,c);
            if(c!='{') d=0;
            break;
        }
    }
    if(StackEmpty(s)&&d==1)
        printf("Matching correctly!!\n");
    else
        printf("Pairing error!!\n");
    return 0;
}

4, The screenshot of the test results is as follows: