用Python语言编写爬取百度图片中猫和狗的图片各100张，将图片存入相应文件夹，两个文件夹分别为cat和dog的代码

这是一个典型的网络爬虫任务，你可以使用python的requests和bs4库来获取网页内容并解析数据，使用urllib库下载图片，代码如下：

import requests
from bs4 import BeautifulSoup
import os
import urllib

# create directories for cat and dog images
if not os.path.exists('cat'):
    os.makedirs('cat')
if not os.path.exists('dog'):
    os.makedirs('dog')

# desired number of images per category
num_images = 100

# define URLs and user agent
cat_url = 'https://www.baidu.com/s?tn=result&ie=utf-8&word=猫'
dog_url = 'https://www.baidu.com/s?tn=result&ie=utf-8&word=狗'
headers = {'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/58.0.3029.110 Safari/537.36'}

# scrape cat images
cat_count = 0
while cat_count < num_images:
    # send GET request to cat URL
    cat_response = requests.get(cat_url, headers=headers)
    cat_soup = BeautifulSoup(cat_response.content, 'html.parser')
    
    # extract image URLs
    cat_images = cat_soup.find_all('img', {'src': True})
    for cat_image in cat_images:
        try:
            # download images to cat folder
            urllib.request.urlretrieve(cat_image['src'], 'cat/cat' + str(cat_count) + '.jpg')
            cat_count += 1
            if cat_count == num_images:
                break
        except:
            continue

# scrape dog images
dog_count = 0
while dog_count < num_images:
    # send GET request to dog URL
    dog_response = requests.get(dog_url, headers=headers)
    dog_soup = BeautifulSoup(dog_response.content, 'html.parser')
    
    # extract image URLs
    dog_images = dog_soup.find_all('img', {'src': True})
    for dog_image in dog_images:
        try:
            # download images to dog folder
            urllib.request.urlretrieve(dog_image['src'], 'dog/dog' + str(dog_count) + '.jpg')
            dog_count += 1
            if dog_count == num_images:
                break
        except:
            continue

该程序首先创建了cat和dog两个目录，用于保存爬虫下载的猫和狗的图片。然后，定义了要爬取的图片数量和要访问的百度搜索结果页面的URL。使用requests库，程序可以以所定义的用户代理发送HTTP GET请求并接收响应，然后使用BeautifulSoup库解析得到的响应内容。程序从HTML标记中提取图片URL并使用Python的urllib库将图片下载到相应的目录中。

请注意，由于百度的反爬虫机制，此代码可能会被禁止访问并返回错误消息。因此，建议您仅在合适的时间间隔内运行该程序，以免触发反爬虫机制并受到不必要的影响。