C语言实现数学表达式运算

#define _CRT_SECURE_NO_DEPRECATE

#define _CRT_SECURE_CPP_OVERLOAD_STANDARD_NAMES 1

#include <stdlib.h>
#include <stdio.h>
#include "myStack.h"

// 判断是否操作符
int ifOp(char c) {
    switch (c) {
    case '+':
        return 1;
    case '-':
        return 1;
    case '*':
        return 1;
    case '/':
        return 1;
    case '(':
        return 1;
    case ')':
        return 1;
    case '#':
        return 1;
    default:
        break;
    }
    return 0;
}

int findOffset(char * str,char c,int len) {
    for (int i = 0; i < len;i++) {
        if (str[i] == c) {
            return i;
        }
    }
    return -1;
}

//判断任意相继出现的2个运算符的优先级
char yxji(char op1,char op2) {
    char ops[] = "+-*/()#";
    char oplist[7][7] = { 
        ">><<<>>",
        ">><<<>>",
        ">>>><>>",
        ">>>><>>" ,
        "<<<<<=&",
        ">>>>&>>",
        "<<<<<&="};
    int len = sizeof(ops) / sizeof(char);
    return oplist[findOffset(ops,op1, len)][findOffset(ops, op2, len)];
}

//基础运算 a-第1个数  b-第2个数
void baseOp(char op,int a,int b,int * value) {
    printf("baseOp %d %c %d",a,op,b);
    //int value = 0;
    //int* p = &value;
    switch (op) {
    case '+':
        *value = a + b;
        break;
    case '-':
        *value = a-b;
        break;
    case '*':
        *value = a*b;
        break;
    case '/':
        *value = a/b;
        break;
    default:
        printf("运算符不合法");
        exit(1);
    }
}

//转换字符为数字
void transValue(char  c,int * v) {
    if (c > 47 && c < 58) {
        *v =  (c - 48);
    }
}

void printstack(MyStack * stack1,MyStack * stack2) {
    int len1 = myListGetSize(stack1);
    int len2 = myListGetSize(stack2);
    printf("stack1值：");
    for (int i = 0; i < len1;i++) {
        char* m = (char*)myListGetDataAt(stack1,i );
        printf("%c ", *m);
    }
    printf("\nstack2值：");
    for (int i = 0; i < len2; i++) {
        int* m = (int*)myListGetDataAt(stack2, i);
        printf("%d(%p) ", *m,m);
    }
    printf("\n");
}

// 计算,该方法只能对数字 0-9 运算(可掌握栈、指针的使用)
// 2*3*(1+2)#
void calculate(char bds[]) {
    int i = 0;
    char flag = '#';
    MyStack* stack1 = createMyStack();//stack1中放运算符
    myStackPush(stack1, &flag);
    MyStack* stack2 = createMyStack();//stack2中放数字
    //char c = bds[i]; // 等价于*(bds+i) 
    while (bds[i] != '#' || *(char*)myStackGetTop(stack1)!='#') {
        printstack(stack1,stack2);
        if (!ifOp(bds[i])) {
             
            int* vu = (int*)malloc(sizeof(int));
            transValue(bds[i], vu);
            printf("is number:%d\n", *vu);//打印出数字
            myStackPush(stack2, vu);
            i++;
        }
        else {
            printf("is fuhao:%c\n", bds[i]);
            char * op1 = (char*)myStackGetTop(stack1);
            printf("top1 op:%c\n",*op1);
            if (*op1 == '#') {
                myStackPush(stack1, &bds[i]);
                i++;
                continue;
            }
            char res = yxji(*op1, bds[i]);
            printf("yxji:%c\n",res);
            switch (res) {
                case '>':{
                    char* curop = (char*)myStackPop(stack1);//取出当前运算符
                    printf("top2 op:%c\n", *op1);
                    int* b = (int*)myStackPop(stack2);//第2个运算数
                    int* a = (int*)myStackPop(stack2);//第1个运算数
                    
                    int* value = (int*)malloc(sizeof(int));
                    baseOp(*curop, *a, *b, value);
                    printf("=%d\n", *value);
                    myStackPush(stack2, value);
                    break;
                }
                case '<':
                    myStackPush(stack1, &bds[i]);
                    i++;
                    break;
                case '=': {
                    printf("()==");
                    myStackPop(stack1);//取出右括号 (
                    i++;
                    break;
                }
                default:
                    printf("表达式错误!");
                    exit(1);
            }
        }
    }
    int * valueRes = (int*)myStackPop(stack2);
    printf("计算结果值为:%d\n",*valueRes);

    freeMyList(stack1);
    freeMyList(stack2);
}

int main() {
    printf("输入表达式：\n");
    char bds[50];
    scanf("%s",bds);// 数组变量名，传入的相当于是数组第一个元素的地址。方法形参是个指针变量，指针变量才能存放地址
    calculate(bds);
    return 0;
}