数据结构初学2

计算器0.1


#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>

#define STACK_INIT_SIZE 20
#define STACKINCREMENT 10
#define MAXBUFFER 10

typedef double SElemType;
typedef struct sqlStack {
    SElemType *base;
    SElemType *top;
    int stackSize;
} sqlStack;

void initStack(sqlStack *S) {
    S->base = (SElemType *)malloc(STACK_INIT_SIZE * sizeof(SElemType));
    if(!S->base) {
        printf("Memory allocate failed!\n");
        exit(EXIT_FAILURE);
    }
    S->top = S->base;
    S->stackSize = STACK_INIT_SIZE;

    printf("Stack has been initialized successfully!\n");
}

/*取到栈顶的元素*/
void getTop(sqlStack S, SElemType *data) {
    if(S.top == S.base) {
        printf("Stack is NULL!\n");
    }
    *data = *(S.top - 1);
}

/*将数据元素压栈*/
void Push(sqlStack *S, SElemType data) {
    if(S->top - S->base > S->stackSize) {
        S->base = (SElemType *)realloc(S->base, (S->stackSize + STACKINCREMENT) * sizeof(SElemType));
        if(!S->base) {
            printf("Memory allocate failed!\n");
            exit(EXIT_FAILURE);
        }
        S->top = S->base + S->stackSize;
        S->stackSize += STACKINCREMENT;
    }
    /*数据元素入栈*/
    *S->top++ = data;
}

/*元素出栈*/
void Pop(sqlStack *S, SElemType *data) {
    if(S->base == S->top) {
        printf("Error: Stack is NULL!\n");
    }
    *data = *--S->top;
}

/*判断栈是否为空*/
int stackEmpty(sqlStack S) {
    if(S.base == S.top)
        return 1;
    else
        return -1;
}

/*获取栈的长度*/
int stackLength(sqlStack S) {
    return S.top - S.base;
}

int main() {
    char opdata;
    int i = 0;
    double operand1, operand2;
    char ops[MAXBUFFER];

    sqlStack S;
    initStack(&S);
// sqlStack OPERAND;
// sqlStack OPERATOR;
// initStack(&OPERAND);
// initStack(&OPERATOR);

    /*如果输入的不是换行符就表示继续接收输入*/
    printf("Please input the string you want to evaluate: ");
    while((opdata = getchar()) != '\n') {
        /*当输入的数据为操作数时，就直接打印在屏幕上*/
        /*过滤掉所有的数字*/
        while(isdigit(opdata) || '.' == opdata) {
            ops[i++] = opdata;

            if(i >= MAXBUFFER) {
                printf("Error : The operand is too big!\n");
                return -1;
            }
            opdata = getchar();
            if(' ' == opdata) {
                ops[i] = '\0';
                operand1 = atof(ops);
                /*如果是数字就入栈，是操作符就出栈*/
                Push(&S, operand1);
                i = 0;
                break;/*跳出循环，输入的数字已经结束*/
            }
        }

        /*当遇到操作符的时候的处理*/
        switch(opdata) {
        case '+':
            Pop(&S, &operand1);
            Pop(&S, &operand2);
            Push(&S, operand2 + operand1);
            break;
        case '-':
            Pop(&S, &operand1);
            Pop(&S, &operand2);
            Push(&S, operand2 - operand1);
            break;
        case '*':
            Pop(&S, &operand1);
            Pop(&S, &operand2);
            Push(&S, operand2 * operand1);
            break;
        case '/':
            Pop(&S, &operand1);
            Pop(&S, &operand2);
            if(0 == operand1) {
                printf("Error : operand1 cannot be zero!\n");
                exit(EXIT_FAILURE);
            } else {
                Push(&S, operand2 / operand1);
                break;
            }
        default:
            continue;
        }
    }
    Pop(&S, &operand1);
    printf("The result is : %lf\n", operand1);

    return 0;
}