I'd like to use yaml-cpp for storeing some config-values. In order to get in touch with yaml-cpp, I've written a method which creates a node (_config is from Type YAML::Node), put some values in it and write it into a file:
void write_config()
{
std::ofstream fout("/home/user/config.yaml");
_config["Foo"]["0"] = "0";
_config["Foo"]["1"] = "1";
_config["Foo"]["2"] = "2";
_config["Foo"]["3"] = "3";
_config["Foo"]["4"] = "4";
_config["Foo"]["5"] = "5";
fout << _config;
}
after running this Method, a valid yaml file is created:
Foo:
1: 1
3: 3
0: 0
5: 5
4: 4
2: 2
After that, I have created a Method to read the file and print some information:
void load_config()
{
_config = YAML::Node("/home/user/config.yaml");
cout << "_config: " << _config << endl;
cout << "doc.Type(): " << _config.Type() << "\n";
cout << "doc.size(): " << _config.size() << "\n";
for (const auto& kv : _config)
{
std::cout << kv.first.as<std::string>() << "\n"; // prints Foo
std::cout << kv.second.as<std::string>() << "\n"; // prints Foo
}
}
but the output is:
_config: /home/user/config.yaml
doc.Type(): 2
doc.size(): 0
could someone tell me why the Node is empty (size == 0) and how I can read the file properly?
Thank you in advance!
I've found my Mistake...
_config = YAML::Node("/home/user/config.yaml");
should be
_config = YAML::LoadFile("/home/user/config.yaml");
Related
I have created pseudo terminal master/slave and read on master side using select with the following code:
fd_set read_fd;
struct timeval timeout;
while (is_running) {
FD_ZERO(&read_fd);
FD_SET(fd, &read_fd);
timeout.tv_sec = 0;
timeout.tv_usec = 500000;
int ret = select(fd + 1, &read_fd, NULL, NULL, &timeout);
std::cout << "select return:" << ret << std::endl;
if (ret == -1) {
std::cerr << "select error:" << strerror(errno) << " code:" << errno << std::endl;
is_running = false;
}
if (FD_ISSET(fd, &read_fd)) {
if (read(fd, buff, size) == -1) {
if (EIO == errno) {
// After first read - Input/output error code:5
std::this_thread::sleep_for(std::chrono::milliseconds(500));
}
std::cerr << "read error:" << strerror(errno) << " code:" << errno << std::endl;
} else {
std::cout << "read:" << buff << std::endl;
}
}
}
std::cout << "read exit" << std::endl;
In terminal I send data from slave to master using
echo "22222222222222" > /dev/pts/23
In case if data send on master side read operation work fine - I see that select returns 1 and data got read but on next iterations in while loop select also returns 1 but read function constantly fails with error EIO and it is not clear for me.
select return:1
read:22222222222222 <------------------------ data read: OK
select return:1
alloc:8 write:7 buff:hello14
read error:Input/output error code:5 <------------------- EIO
select return:1
read error:Input/output error code:5 <------------------- EIO
Could you please help me to understood on why after first read (echo "22222222222222" > /dev/pts/23 on slave) select returns 1 but all read operations fails with EIO error.
I am trying to save the data the user inputted inside a linked-list and then store those data inside a file so that I can retrieve them back when I enter the 2nd option(as per in the int main()). Unfortunately, after I wrote the data into the file and check back the file, I found out that my data is missing and the file is filled with garbage.so I cant retrieve the data back. Is there any solution to this problem?? Thank you.
#include<iostream>
#include<cstdlib>
#include<iomanip>
#include<fstream>
using namespace std;
fstream fp;
class List{
private:
struct node{
string name;
string surname;
int idNum;
string nationality;
int number;
node *next;
}nod;
node* head;
node* curr;
node* temp;
public:
List();
bool isEmpty(node *head){
if(head==NULL){
return true;
}
else
return false;
}
void AddNode(string addName,string addsurName,int addId,string addNation,int addNumber);
void insertAsFirst(string addName,string addsurName,int addId,string addNation,int addNum);
//void DeleteNode(int delData);
void printList();
void write_linky(string name,string surName,int idNum,string nation,int number);
void read_linky();
}lb;
List::List(){
head=NULL;
curr=NULL;
temp=NULL;
}
void List::insertAsFirst(string addName,string addsurName,int addId, string addNation,int addNum){
node *n = new node;
n->name=addName;
n->surname=addsurName;
n->idNum=addId;
n->nationality=addNation;
n->number=addNum;
n->next = NULL;
head = n;
//last = temp;
}
void List::AddNode(string addName,string addsurName,int addId,string addNation,int addNum){
if(isEmpty(head)){
insertAsFirst(addName,addsurName,addId,addNation,addNum);
}
else{
node* n = new node;
n->next=NULL;
n->name=addName;
n->surname=addsurName;
n->idNum=addId;
n->nationality=addNation;
n->number=addNum;
curr = head;
while(curr->next != NULL){
curr = curr->next;
}
curr->next = n;
}
}
void List::printList(){
curr=head;
cout << "\n\t\t\t\t CUSTOMER INFO" << endl << endl;
cout <<"NAME" << setw(20) << "SURNAME" << setw(20) << "ID NO. " << setw(20) << "NATIONALLITY" << setw(20) << "TELEPHONE" << endl << endl;
while(curr != NULL){
cout << curr -> name << setw(20) << curr -> surname << setw(20) << curr -> idNum << setw(20) << curr -> nationality << setw(20) << curr -> number << endl << endl;
curr=curr->next;
/*cout<<curr->number << endl;
cout<<curr->age << endl;
cout<<curr->idNum << endl;
cout<<curr->name<< endl;
cout<<curr->surname << endl;
cout<<curr->nationality << endl;
curr = curr->next;
}
*/
}
}
void List::write_linky(string name,string surName,int idNum,string nation,int number)
{
fp.open("Link.dat",ios::out|ios::app);
lb.AddNode(name,surName,idNum,nation,number);
lb.printList();
fp.write((char*)&nod,sizeof(node));
fp.close();
cout<<"\n\nThe Data Has Been Added ";
}
void List::read_linky(){
fp.open("Link.dat",ios::in);
while(fp.read((char*)&nod,sizeof(node)))
{
lb.printList();
//cout<<"\n\n=====================================================\n";
//getch();
}
fp.close();
//getch();
}
int main(){
List lb;
int idNum,number;
string name,surname,nationality;
char choice,ch;
cout<<"Please select your choice"<<endl;
cout<<"1.Book ticket"<<endl;
cout<<"2.view details"<<endl;
cin>>ch;
switch(ch){
case '1':
do{
cout<< "Enter name: ";
cin>>name;
cout<< "Enter surname: ";
cin>>surname;
cout<< "Enter identification number: ";
cin>>idNum;
cout<< "Enter your nationality: ";
cin>>nationality;
cout<< "Enter contact number: ";
cin>>number;
lb.write_linky(name,surname,idNum,nationality,number);
//lb.AddNode(number,age,idNum,name,surname,nationality);
cout<<"\n\nDo you want to add more entry?";
cin>>choice;
}while(choice=='y');
break;
case '2':
lb.read_linky();
break;
}
}
//lb.printList();
I've never done this but I'd guess string is a complex structure that doesn't lend itself to being written to disk like this. As a test change these to (say) char[255] and it might be happier.
I have some code that typeid does not print the runtime object type. The code example is:
class interface
{
public:
virtual void hello()
{
cout << "Hello interface: " << typeid(interface).name() << endl;
}
virtual ~interface() {}
};
class t1 : public interface
{
public:
virtual void hello ()
{
cout << "Hello t1: " << typeid(t1).name() << endl;
}
};
class t2 : public t1
{
public:
void hello ()
{
cout << "Hello t2: " << typeid(t2).name() << endl;
}
};
......
interface *p;
t1 *p1;
t2 *p2, *pt2;
t3 *p3, *pt3;
pt2 = new t2;
std::cout << "type1: " << abi::__cxa_demangle(typeid(pt2).name(), 0, 0, &status) << "\n\n";
p = pt2;
assert(p != NULL);
p->hello();
std::cout << "type2: " << abi::__cxa_demangle(typeid(p).name(), 0, 0, &status) << "\n\n";
p1 = dynamic_cast<t1 *>(p);
assert(p1 != NULL);
p1->hello();
std::cout << "type3: " << abi::__cxa_demangle(typeid(p1).name(), 0, 0, &status) << "\n\n";
p2 = dynamic_cast<t2 *>(p);
assert(p2 != NULL);
p2->hello();
std::cout << "type4: " << abi::__cxa_demangle(typeid(p2).name(), 0, 0, &status) << "\n\n";
I build the program with "g++ -g -o ...". Then the output is:
type1: t2*
Hello t2: 2t2
type2: interface*
Hello t2: 2t2
type3: t1*
Hello t2: 2t2
type4: t2*
The print output seems right. But I expect type2 to be t2* too for RTTI. However, output is interface*. I expect type3 to be t2* too. Anything wrong?
std::typeid gives you dynamic type information only if you pass it an object that has dynamic type, but pointers are not considered to have dynamic type since they do not contain any virtual methods.
So if you do std::typeid(*p) you'll get what you're looking for
I'm using boots's property_tree library. I'm looking for a way to get a child node from a ptree object, but return an empty ptree if failed. I came across a nice example in property_tree/examples/empty_ptree_trick.cpp:
void process_settings(const std::string &filename)
{
ptree pt;
read_info(filename, pt);
const ptree &settings = pt.get_child("settings", empty_ptree<ptree>());
std::cout << "\n Processing " << filename << std::endl;
std::cout << " Setting 1 is " << settings.get("setting1", 0) << std::endl;
std::cout << " Setting 2 is " << settings.get("setting2", 0.0) << std::endl;
std::cout << " Setting 3 is " << settings.get("setting3", "default") << std::endl;
}
which does exactly what I need. The problem is that the compiler complains that empty_ptree() function is not a member of boost:property_tree. Any ideas where empty_ptree() is?
I'm using boost 1.44 on VS2010.
I have just blown a full day trying to answer that question!
This was my solution. Firstly I used pointers, and not references as you have to initialize them immediately. Then I just caught the exception and added a new ptree.
using namespace boost::property_tree;
ptree r_pt;
ptree *c_pt;
read_xml( "file.xml" , r_pt);
try {
c_pt = &(r_pt.get_child( "example" ));
}
catch (ptree_bad_path) {
c_pt = &(r_pt.put_child( "example", ptree() ));
}
std::cout << "Setting 1 is " << c_pt.get("setting1", 0) << std::endl;
From what I could pick up they expect us to use the boost::optional type. But I'm just a beginner..
EDIT
I just found the implementation of empty_ptree<>.
template<class Ptree>
inline const Ptree &empty_ptree()
{
static Ptree pt;
return pt;
}
I think you can just add this to your code and use it as described in the empty_ptree_trick.cpp, but I am sticking with my solution for now untill I find out how its actually supposed to be done.
void process_settings(const std::string &filename)
{
ptree pt;
read_info(filename, pt);
const ptree &settings = pt.get_child("settings", ptree());
std::cout << "\n Processing " << filename << std::endl;
std::cout << " Setting 1 is " << settings.get("setting1", 0) << std::endl;
std::cout << " Setting 2 is " << settings.get("setting2", 0.0) << std::endl;
std::cout << " Setting 3 is " << settings.get("setting3", "default") << std::endl;
}
Note, that will prevent throwing an instance of 'boost::wrapexceptboost::property_tree::ptree_bad_path'
I have a class (contains a few scalar values and a vector of floats) and I want to read and write an instance as the value of another map.
// write
out << YAML::Key << "my_queue" << YAML::Value << my_queue;
// read (other code cut out...)
for (YAML::Iterator it=doc.begin();it!=doc.end();++it)
{
std::string key, value;
it.first() >> key;
it.second() >> value;
if (key.compare("my_queue") == 0) {
*it >> my_queue;
}
}
Writing this class works perfectly, but I can't seem to read it no matter what I do. It keeps throwing an InvalidScalar.
Caught YAML::InvalidScalar yaml-cpp: error at line 20, column 13: invalid scalar
and this is that the output (written with yaml-cpp without it reporting any errors) looks like:
Other Number: 80
my_queue:
size: 20
data:
- 3.5
- -1
- -1.5
- 0.25
- -24.75
- -5.75
- 2.75
- -33.55
- 7.25
- -11
- 15
- 37.5
- -3.75
- -28.25
- 18.5
- 14.25
- -36.5
- 6.75
- -0.75
- 14
max_size: 20
mean: -0.0355586
stdev: 34.8981
even_more_data: 1277150400
The documentation seems to say this is supported usage, a nested map, in this case with a sequence as one of the values. It complains about it being an InvalidScalar, even though the first thing I do it tell it that this is a map:
YAML::Emitter& operator << ( YAML::Emitter& out, const MeanStd& w )
{
out << YAML::BeginMap;
out << YAML::Key << "size";
out << YAML::Value << w.size();
out << YAML::Key << "data";
out << YAML::Value << YAML::BeginSeq;
for(Noor::Number i=0; i<w.size(); ++i) {
out << w[i];
}
out << YAML::EndSeq;
out << YAML::Key << "max_size";
out << YAML::Value << w.get_max_size();
out << YAML::Key << "mean";
out << YAML::Value << w.mean();
out << YAML::Key << "stdev";
out << YAML::Value << w.stdev();
out << YAML::EndMap;
return out;
}
Does anyone see a problem with this?
When you're reading the YAML:
std::string key, value;
it.first() >> key;
it.second() >> value; // ***
if (key.compare("my_queue") == 0) {
*it >> my_queue;
}
The marked line tries to read the value of the key/value pair as a scalar (std::string); that's why it tells you that it's an invalid scalar. Instead, you want:
std::string key, value;
it.first() >> key;
if (key.compare("my_queue") == 0) {
it.second() >> my_queue;
} else {
// ...
// for example: it.second() >> value;
}
YAML::Node internalconfig_yaml = YAML::LoadFile(configFileName);
const YAML::Node &node = internalconfig_yaml["config"];
for(const auto& it : node )
{
std::cout << "\nnested Key: " << it.first.as<std::string>() << "\n";
if (it.second.Type() == YAML::NodeType::Scalar)
{
std::cout << "\nnested value: " << std::to_string(it.second.as<int>()) << "\n";
}
if (it.second.Type() == YAML::NodeType::Sequence)
{
std::vector<std::string> temp_vect;
const YAML::Node &nestd_node2 = it.second;
for(const auto& it2 : nestd_node2)
{
if (*it2)
{
std::cout << "\nnested sequence value: " << it2.as<std::string>() << "\n";
temp_vect.push_back(it2.as<std::string>());
}
}
std::ostringstream oss;
std::copy(temp_vect.begin(), temp_vect.end(),
std::ostream_iterator<std::string>(oss, ","));
std::cout << "\nnested sequence as string: " <<oss.str() << "\n";
}
}
if (it2.second.Type() == YAML::NodeType::Map)
{
// Iterate Recursively again !!
}