该继续看ifstream类了。
ifstream继承自istream类,istream类只有一个iostream库中创建好的cin对象,对应一个输入设备就是pc机的键盘,而ifstream类则没有在fstream中有创建好的对象,原因上一篇文章已经说了。
ifstream是文件输入类,输入的源是文件,目标是内存,从文件向内存输入,也就是读取文件的意思了。
如果想读取一个文件,简单的示例代码如下:
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get方法会读取一个字符,当读到文件末尾就会返回false。
并且示例了_SH_DENYRW的共享方式打开文件的后果,在第一个暂停处无法打开c:\1.txt,当调用close才可以正常打开。
主要工作函数:
get
getline
read
另外有几个辅助函数:
peek
putback
ignore
gcount
seekg
seekdir
tellg
实际开发过程中使用std::getline这个全局函数来获取一行字符,使用如下:
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