stringstream ssin(line);
时间: 2023-06-05 21:48:08 浏览: 173
stringstream ssin(line);是一个C++中的语句,它的作用是将字符串line转换为一个stringstream类型的对象ssin,以便对该字符串进行输入输出操作。stringstream是C++标准库中的一个类,它可以将字符串转换为各种数据类型,比如整型、浮点型、字符型等等。在这个语句中,ssin是一个对象名,line是一个字符串变量名。
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stringstream
stringstream is a class in the C++ Standard Library that allows us to treat a string as a stream of characters, which can be read from and written to like any other stream. It provides several methods for converting between strings and other data types, such as integers and floating-point numbers.
The stringstream class is useful for parsing input strings and converting them into different data types, or for constructing output strings from different data types. It is commonly used in situations where we need to manipulate strings and perform operations on them, such as parsing command-line arguments or reading and writing data to files.
To use stringstream, we first include the <sstream> header file. We can then create an instance of the stringstream class, and use its methods to read from or write to the underlying string.
For example, the following code creates a stringstream object and uses it to convert a string to an integer:
```
#include <iostream>
#include <sstream>
int main() {
std::string str = "42";
std::stringstream ss(str);
int num;
ss >> num;
std::cout << "The number is: " << num << std::endl;
return 0;
}
```
In this code, we create a stringstream object `ss` initialized with the string `str`. We then use the `>>` operator to extract an integer from the stream and store it in the `num` variable. Finally, we print the value of `num` to the console.
stringstream is a powerful tool that allows us to manipulate strings with ease, and is a valuable addition to any C++ programmer's toolkit.
while (getline(infile, line)) { stringstream ss(line); string name, password, websiteName; vector<int> visitCount; ss >> name >> password; addUser(name, password); int userId = users.size() - 1; while (ss >> websiteName) { int count; while (ss >> count) { visitCount.push_back(count); } addWebsite(userId, websiteName, visitCount); visitCount.clear(); } }是什么意思
这段代码是用来从一个文件中读取用户信息的。文件中每一行包含用户的姓名、密码、访问过的网站名称和对应网站的访问次数。代码首先使用getline()函数从文件中读取一行,然后使用stringstream将这一行分解成多个部分(姓名、密码、网站名称和对应访问次数),并将它们存储到相应的变量中。接着,代码调用addUser()函数将新用户的姓名和密码添加到用户列表中,并获得该用户的ID。然后,代码使用while循环遍历网站名称和对应的访问次数,将它们添加到访问记录中,并调用addWebsite()函数将用户的访问记录添加到相应的网站中。最后,代码清空visitCount向量,以便下一个网站的访问记录能够正确地添加到其中。