基于C语言的表达式求值问题

表达式求值问题

#include
#define StackSzie 100
#define QueueSize 100

/*队列的相关操作*/

typedef char DataType;

typedef struct {
    char data[100];
    int front, rear;
}SeqQueue;

/*初始化队列*/
void InitQueue(SeqQueue *Q) {
    Q->front = 0;
    Q->rear = 0;
}

/*判断空队列*/
int QueueEmpty(SeqQueue Q) {
    return Q.rear == Q.front;
}

/*入队列*/
void EnQueue(SeqQueue *Q,DataType x) 
{
    if ((Q->rear+1)% QueueSize ==Q->front) {
        printf("Queue overflow");
    }
    else {
        Q->data[Q->rear] = x;
        Q->rear = (Q->rear+1) % QueueSize;
    }
}


/**/
DataType DeQueue(SeqQueue *Q) {
    char x;
    if (QueueEmpty(*Q)) return 0;
    else {
        x = Q->data[Q->front];
        Q->front = (Q->front+1)%QueueSize;
        return x;
    }
}


/*栈的相关操作*/
typedef struct {
    DataType data[100];
    int top;
}SeqStack;


/*初始化栈*/
void InitStack(SeqStack *S) {
    S->top = -1;
}


/*入栈*/
void Push(SeqStack *S, DataType x) {
    if (S->top == StackSzie - 1) {
        printf("stack overflow");
    }
    else {
        S->top = S->top + 1;
        S->data[S->top] = x;
    }
}


/*退栈*/
DataType Pop(SeqStack *S) {
    if (S->top == -1) {
        printf("stack underflow");
        return 0;
    }
    else
        return S->data[S->top--];
}


/*取栈顶元素*/
DataType GetTop(SeqStack S) {
    if (S.top == -1) {
        printf("stack empty");
        return 0;
    }
    else
        return S.data[S.top];
}


/*求运算符优先级函数*/
int Priority(DataType op) {
    switch (op)
    {
        case '(':
        case '#':return 0;
        case '-':
        case '+':return 1;
        case '*':
        case '/':return 2;
    }
    return -1;
}


void CTpostExp(SeqQueue *Q) 
{
    SeqStack S;     //运算符栈
    printf("请输入运算表达式，并用#结尾!\n");
    char c, t;
    InitStack(&S);
    Push(&S, '#');
    do {
        c = getchar();
        switch (c)
        {
        case ' ':break;         //去除空格 
        case '0':
        case '1':
        case '2':
        case '3':
        case '4':
        case '5':
        case '6':
        case '7':
        case '8':
        case '9':   EnQueue(Q, c);break;
        case '(':   Push(&S, c);break;
        case ')':
        case '#':
            do {
                t = Pop(&S);
                if (t != '(' && t != '#')   EnQueue(Q, t);
            }while (t != '(' && S.top != -1);
            break;
        case '+':
        case '-':
        case '*':
        case '/':
            while (Priority(c) <= Priority(GetTop(S)))
            {
                t = Pop(&S);
                EnQueue(Q, t);
            }
            Push(&S, c);
            break;
        }//EndSwitch
    } while (c !='#');              //以#为结束表达式扫描
    printf("\n导入成功！\n");
}


/*后缀表达式的计算*/
DataType CPostExp(SeqQueue Q) {
    SeqStack S;
    char ch;
    int x, y;
    InitStack(&S);
    while(!QueueEmpty(Q)) {
        ch = DeQueue(&Q);
        if (ch >= '0' && ch <= '9')
            Push(&S,ch);
        else {
            y = Pop(&S) - '0';
            x = Pop(&S) - '0';
            switch (ch)
            {
                case '+':Push(&S, (char)(x+y+'0'));break;
                case '-':Push(&S, (char)(x-y+'0'));break;
                case '*':Push(&S, (char)(x*y+'0'));break;
                case '/':Push(&S, (char)(x/y+'0'));break;
            }
        }
    }
    return GetTop(S);
}

/*主函数*/
int main(void) {
    SeqQueue Q;
    InitQueue(&Q);
    CTpostExp(&Q);
    printf("表达式的运算结果是：%c\n",CPostExp(Q));
    printf("表达式的后缀表达式为：");
    while (!QueueEmpty(Q))
        printf("%2c",DeQueue(&Q));
    printf("\n");
}