用栈stack实现简单计算器 c++

好的，这个问题非常适合用程序解决。以下是用stack实现简单计算器的c代码示例：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

#define STACKLEN 1000   /* 栈的最大容量 */

typedef struct {
    int top;            /* 栈顶指针 */
    double data[STACKLEN]; /* 元素数组 */
} Stack;

void push(Stack *pstack, double value) {
    if (pstack->top == STACKLEN - 1) {
        printf("Error: stack overflow!\n");
        exit(EXIT_FAILURE);
    } else {
        pstack->data[++pstack->top] = value;
    }
}

double pop(Stack *pstack) {
    if (pstack->top == -1) {
        printf("Error: stack underflow!\n");
        exit(EXIT_FAILURE);
    } else {
        return pstack->data[pstack->top--];
    }
}

bool is_digit(char c) {
    return (c >= '0' && c <= '9');
}

int precedence(char op) {
    if (op == '+' || op == '-') return 1;
    else if (op == '*' || op == '/') return 2;
    else return 0;
}

double calculate(double left, char op, double right) {
    switch (op) {
        case '+': return left + right;
        case '-': return left - right;
        case '*': return left * right;
        case '/': return left / right;
        default:
            printf("Error: invalid operator!\n");
            exit(EXIT_FAILURE);
    }
}

double eval(char *expr) {
    Stack operandStack;
    operandStack.top = -1;

    Stack operatorStack;
    operatorStack.top = -1;

    int len = strlen(expr);
    int i = 0;

    while (i < len) {
        char c = expr[i];

        if (is_digit(c)) {
            double value = 0.0;
            while (i < len && is_digit(expr[i])) {
                value = value * 10.0 + (double)(expr[i] - '0');
                i++;
            }
            push(&operandStack, value);
        } else {
            while (operatorStack.top != -1
                   && precedence(operatorStack.data[operatorStack.top]) >= precedence(c)) {
                char op = operatorStack.data[operatorStack.top--];
                double right = pop(&operandStack);
                double left = pop(&operandStack);
                push(&operandStack, calculate(left, op, right));
            }
            push(&operatorStack, c);
            i++;
        }
    }

    while (operatorStack.top != -1) {
        char op = operatorStack.data[operatorStack.top--];
        double right = pop(&operandStack);
        double left = pop(&operandStack);
        push(&operandStack, calculate(left, op, right));
    }

    return pop(&operandStack);
}

int main() {
    char s[1000];
    printf("Please enter an expression: ");
    scanf("%s", s);
    double result = eval(s);
    printf("Result: %f\n", result);
    return 0;
}

这段代码定义了两个栈：一个操作数栈（operandStack）和一个操作符栈（operatorStack），通过不断入栈和出栈的操作，实现对表达式进行求值。其中，is_digit函数用于判断一个字符是否是数字；precedence函数用于比较两个运算符的优先级；calculate函数用于计算两个操作数和一个操作符的运算结果；eval函数是主函数，用于将输入的表达式转化为数字计算结果。

希望这个回答能够帮助您！