通过键盘输入100以内正整数的加、减运算式，请编写一个程序输

#我自己测试了几个对着呢，不足之处还望大家指教
while True:
    try:
        list_in = input().split()
        if len(list_in) != 3:
            print('0')
        elif list_in[1] == '+' and (list_in[0])>'0' and list_in[2]>'0':
            result = int(list_in[0]) + int(list_in[2])
            print(str(result))          
        elif list_in[1] == '-' and list_in[0]>'0' and list_in[2]>'0':
            result = int(list_in[0]) - int(list_in[2])
            print(str(result))
        else:      
             print('0')
    except:
        break

#include <iostream>    
using namespace std;    
    
void arithmetic(const char *pInputStr, long lInputLen, char *pOutputStr)    
{       
    const char *input = pInputStr;    
    char *output = pOutputStr;    
    int sum = 0;    
    int operator1 = 0;    
    int operator2 = 0;    
    char *temp = new char[5];    
    char *ope = temp;    
    while(*input != ' ') //获得操作数1    
    {    
        sum = sum*10 + (*input++ - '0');    
    }    
    input++;    
    operator1 = sum;    
    sum = 0;    
    
    while(*input != ' ')    
    {    
        *temp++ = *input++;    
    }    
    
    input++;    
    *temp = '\0';    
    
    if (strlen(ope) > 1 )    
    {    
        *output++ = '0';    
        *output = '\0';    
        return;    
    }    
    
    while(*input != '\0') //获得操作数2    
    {    
        sum = sum*10 + (*input++ - '0');    
    }    
    operator2 = sum;    
    sum = 0;    
    
    switch (*ope)    
    {    
        case '+':itoa(operator1+operator2,pOutputStr,10);    
            break;    
        case '-':itoa(operator1-operator2,pOutputStr,10);    
            break;    
        default:    
            *output++ = '0';    
            *output = '\0';    
        return;    
    }    
}    
    
int main()    
{    
    char input[] = "4 - 7";    
    char output[] = "    ";    
    arithmetic(input,strlen(input),output);    
    cout<<output<<endl;    
    return 0;    
}