题解 | #表达式求值#

计算通用

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

static int i = 0;

static int compate(char *str)
{
    if(!str)
    {
        return -1;
    }
    int stack[1000] = {0};
    int top = -1;
    int len = strlen(str);
    //printf("str:[%s : %d]\n", str, len);
    char flag = '+';    //默认'+’号
    while(i < len)
    {
        int num = 0;
        if(str[i] == '-')
        {
            i++;
            flag = '-';
        }
        if(str[i] == '(')
        {
            i++;
            num = compate(str);
        }

        while(str[i] >= '0' && str[i] <= '9')
        {
            num = num*10 + (str[i]-'0');
            i++;
        }
        switch(flag)
        {
            case '+':
                {
                    stack[++top] += num;
                }
                break;
            case '-':
                {
                    stack[++top] -= num;
                }
                break;
            case '*':
                {
                    stack[top] *= num;
                }
                break;
            case '/':
                {
                    stack[top] /= num;
                }
                break;
            default:
                break;
        }
        flag = str[i];
        if(str[i] == ')')
        {
            i++;
            break;
        }
        i++;
    }
    int res = 0;
    for(int j = 0; j <= top; j++)
    {
        res += stack[j];
    }
    return res;
}

int main()
{
    char str[1000] = {0};
    gets(str);
    int res = compate(str);
    printf("%d\n", res);
    return 0;
}