我想阅读书籍 - txt 文件中的书名、作者和价格。The 3 properties of the book are separated by '|' - Title|Author|Book.
但是,我不知道如何做到这一点。我有结构 Book,有 3 个元素。我想,对于每行读取书名,作者和价格,将它们分别保存到结构的3个变量中并在控制台上打印它们。我试图只用标题来做这个,但它打印了整行。请问如何分别打印每本书的作者名称和价格?
您将需要的包含库以及您的Book
结构定义。一旦开始学习稍微更高级的 C++ 主题,您就可以学习如何为输入和输出流重载友元函数,以使您的 I/O 操作独立于Book
对象。
#include <iostream> ///< std::cout
#include <fstream> ///< std::ifstream
#include <sstream> ///< std::istringstream, std::string
#include <vector> ///< std::vector
struct Book
{
std::string title; ///< title of the book
std::string author; ///< author of the book
std::string price; ///< price of the book (TODO use float instead?)
// TODO consider friend std::istream& operator>> for parsing input data
// TODO consider friend std::ostream & operator<< for printing object
};
如果您有输入文件的句柄,则可以像这样解析它。一次阅读每一行。在 input.eof() 之前不要阅读,因为它是错误的!将每一行存储到一个临时std::istringstream
对象中以供进一步解析。使用重载的std::getline(stream, token, delimiter)
with|
来解析行中的数据,直接保存到你的临时Book
对象中。最后,如果您希望以后能够处理它们,请将对象存储到您的向量中,并可选择将它们打印到控制台。
void readBooks(std::ifstream& input, std::vector<Book>& books)
{
std::string line;
while (std::getline(input, line)) ///< while we have a line to parse
{
std::istringstream iss(line); ///< line to parse as sstream
Book book; ///< temporary book object
std::getline(iss, book.title, '|');
std::getline(iss, book.author, '|');
std::getline(iss, book.price, '|');
books.push_back(book); ///< add book object into vector
std::cout << "Title: " << book.title << std::endl;
std::cout << "Author: " << book.author << std::endl;
std::cout << "Price: " << book.price << std::endl << std::endl;
}
}
int main()
{
std::vector<Book> books; ///< store each Book object
std::ifstream input("books.txt");
if (input.is_open())
{
readBooks(input, books); ///< read your books
}
return 0;
}
使用以下输入文件内容进行测试
Tales from Shakespeare (1807)|Shakespeare|6.74 The Jungle Book (1894)|Rudyard Kipling|9.99 Through the Looking-Glass (1871)|Lewis Carroll|12.97
产生了以下结果
Title: Tales from Shakespeare (1807) Author: Shakespeare Price: 6.74 Title: The Jungle Book (1894) Author: Rudyard Kipling Price: 9.99 Title: Through the Looking-Glass (1871) Author: Lewis Carroll Price: 12.97
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