Question

#‎include‬ <iostream>
#include <ctype.h>

using namespace std;
typedef char Txt80[80];

int main()
{
 char *PText;

 Txt80 Txt = "Ur2GReAt";
 int N = 6;
 PText = Txt;

 while (N >=3)
 {
  Txt[N] = (isupper(Txt[N] ? tolower(Txt[N]):toupper(Txt[N])));
  cout << PText <<endl;
  N--;
  PText++;
 }
}

Output is :
 Ur2GRe
 r2GR
 2G

根据循环中使用的三元运算符，我很困惑，如果第6个值是小写字母，它应该将其转换为大写。这里'e'是小写的，但输出仍然是小写的，它只是在循环的第一次运行中打印前6个字符。然后在第二轮中N减少并从2打印。请解释

Answer 1

看起来像这一行：

import scrapy
import json

class RentObject(scrapy.Item):
    address = scrapy.Field()
    purpose = scrapy.Field()
    # Add more fields as needed

class ScrapeSpider(scrapy.Spider):

    name = "rent_hk"
    allowed_domains = ['591.com.hk']
    start_urls = ['http://rent.591.com.hk/?hl=en-us#list' ]

    page_number = 0
    page_num_max = 5 # for test purposes grab only up to 5 pages

    def parse(self, response):

        if 'page_number' in response.meta:
            result_dict = json.loads(response.body)  # get data as dict
            for object in result_dict['items']:
                ro = RentObject()
                ro['address'] = object['address']
                ro['purpose'] = object['purpose']
                yield ro

        # Make request for (next page) JSON data
        self.page_number += 1

        payload = {
            'm': 'home',
            'c': 'search',
            'a': 'rslist',
            'type': '1',
            'p': str(self.page_number),
            'searchtype': '1'
        }

        if self.page_number < self.page_num_max:
            request = scrapy.FormRequest(url='http://rent.591.com.hk/',
                                         method='GET',
                                         formdata=payload,
                                         headers={'Referer': 'http://rent.591.com.hk/?hl=en-us',
                                                  'X-Requested-With': 'XMLHttpRequest'},
                                         callback=self.parse)
            request.meta['page_number'] = self.page_number
            yield request

将Txt[N] = (isupper(Txt[N] ? tolower(Txt[N]):toupper(Txt[N])));设置为零，从而有效地截断字符串。但是，支持的配置看起来很可疑 - 我想知道你是否意味着：

Txt[N]

如何在C ++中解决这个输出

1 个答案: