我正在创建一个函数来接受对文件系统上的路径的引用,并递归地将文件名添加到向量中。但首先我必须能够向矢量添加路径。
这种方法有什么问题?
namespace filesys = boost::filesystem;
方法:
void recursive_file_list(filesys::path & root_path, vector<filesys::path> & paths) {
paths->push_back(*root_path); // line 14
// TODO: add more logic to actually recurse through file system
// for now just add root_path (even though root_path is path of directory, not file)
}
我称之为:
int main(int argc, char* argv[]) {
// Use the command line arguments
filesys::path abs_path; // line 23
if ( argc > 1 )
// Make the system complete this path to absolute path
abs_path = filesys::system_complete( filesys::path( argv[1] ) );
else {
// If no arguments given
cout << "usage: list_files [path]" << endl;
exit(1);
}
// Is this a valid path?
if (!filesys::exists( abs_path )) {
cout << "The path you have specified does not exist." << endl;
exit(2);
}
// If this is a directory
vector<filesys::path> filepaths();
if (filesys::is_directory( abs_path )) {
cout << "You have specified a directory." << endl;
recursive_file_list(&abs_path, &filepaths);
}
else {
cout << "You have specified a file." << endl;
}
}
错误:
list_files.cpp: In function 'void recursive_file_list(boost::filesystem3::path&, std::vector<boost::filesystem3::path, std::allocator<boost::filesystem3::path> >&)':
list_files.cpp:14: error: base operand of '->' has non-pointer type 'std::vector<boost::filesystem3::path, std::allocator<boost::filesystem3::path> >'
list_files.cpp:14: error: no match for 'operator*' in '*root_path'
list_files.cpp: In function 'int main(int, char**)':
list_files.cpp:43: error: invalid initialization of non-const reference of type 'boost::filesystem3::path&' from a temporary of type 'boost::filesystem3::path*'
list_files.cpp:13: error: in passing argument 1 of 'void recursive_file_list(boost::filesystem3::path&, std::vector<boost::filesystem3::path, std::allocator<boost::filesystem3::path> >&)'
我不明白 - 我通过引用传递它然后解除引用它以添加它...不确定我做错了什么。
答案 0 :(得分:4)
您不能取消引用参考! *
和->
运算符不适用于引用;你可以将path
本身推送到vector
本身:
paths.push_back(root_path); // line 14
此外,您不会将地址传递给引用参数,只传递参数本身,因此您可以像这样调用函数:
recursive_file_list(abs_path, filepaths);
引用本身具有类似指针的非复制语义;你不需要通过接收地址或试图取消引用来帮助他们。