堆栈的应用--用C语言实现平衡符号

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/*Check if parenthesis ( ), brackets [ ], and braces { } are balanced.栈的应用————平衡符号by gongzh2011.3.12*//*算法思想:Algorithm{    Make an empty stack;    while(read in a character ch)    {        if( ch is a open symbol)                push(c,S);        else if(ch is a close symbol)            {                if(IsEmpty){error;exit;}                else                {                    if(Top(S) is not match ){error,exit;}                    else pop(S);                }            }        }//end whlile-loop        if(emis not empty){error;exit;}}*/#include <stdio.h>#include <stdlib.h>#define Error(Str) fprintf(stderr,"%s\n",Str),exit(1)struct Node{    char elem;    struct Node *next;};//栈的链表实现typedef struct Node *Stack;int CheckSymbol(Stack S);//检测平衡符号的函数Stack CreateStack(void);/*创建一个空栈*/void MakeEmpty(Stack);int IsEmpty(Stack);//测试栈是否是空栈void Push(char ,Stack);//入栈void Pop(Stack);//出栈char Top(Stack);//获取栈顶元素void DisposeStack(Stack);//销毁栈int main(){    Stack S;    S=CreateStack();    if(CheckSymbol(S))        printf("wrong\n");    else         printf("right\n");        DisposeStack(S);    return 0;}int CheckSymbol(Stack S){    char ch;    printf("input characters as {,} or (,)or [,] \n");    printf("and # to quit\n");    while((ch=getchar())!='#')//输入平衡字符    {        if(ch=='{'||ch=='['||ch=='(')        /*开放符号*/            Push(ch,S);        else if(ch=='}'||ch==']'||ch==')')    /*封闭符号*/            {                if(IsEmpty(S))        /*栈里无字符*/                    Error("stack is empty.");                else                 {                    switch(ch)                    {                        case '}':                            if(Top(S)!='{')//不匹配                            Error("not match");                            else                             break;//匹配成功                                                case ')':if(Top(S)!='(')                            Error("not match");                            else                             break;                                                 case ']':if(Top(S)!='[')                            Error("not match");                            else break;                     }                    /*匹配成功，将栈中匹配成功的符号弹出*/                    Pop(S);                }            }        }    if(!IsEmpty(S))//如果最后栈里还有字符，则说明未匹配完，即出错        Error("the stack is not empty last");    else         return 0;//成功}/*栈的基本操作——链表实现*/Stack CreateStack(void){    Stack S;    S=malloc(sizeof(struct Node));    if(S==NULL)        Error("out of space");    S->next=NULL;    MakeEmpty(S);        return S;    }void MakeEmpty(Stack S){    if(S==NULL)    //未创建栈        Error("must usr CreateStack first");    else        while(!IsEmpty)            Pos(S);}int IsEmpty(Stack S){    return S->next==NULL;}void Push(char ch,Stack S){    Stack tmp;    tmp=malloc(sizeof(struct Node));    if(!tmp)        Error("out of space");        tmp->elem=ch;    tmp->next=S->next;    S->next=tmp;    }void Pop(Stack S){    Stack tmp;    if(IsEmpty(S))        Error("empty stack");    else    {        tmp=S->next;        S->next=tmp->next;        free(tmp);    }}char Top(Stack S){    if(!IsEmpty(S))        return S->next->elem;    Error("empty stack.");    return 0;}void DisposeStack(Stack S){    if(S==NULL)        Error("no stack");    MakeEmpty(S);    free(S);}

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