Here is an example feed that I would like to parse:
https://gdata.youtube.com/feeds/api/users/aniBOOM/subscriptions?v=2&alt=json
You can check it with http://json.parser.online.fr/ to see what it contains.
I have a small problem while parsing data feed provided by youtube. First issue was the way the youtube provided the data wrapped inside feed field and because of that I couldn't parse the username straight from original json file so I had to parse first entry field and generate new Json data from that.
Anyway the problem is that for some reason that doesn't include more than the first username and I don't know why because if you check that feed on online parser the entry should contain all the usernames.
`
data = value["feed"]["entry"];
Json::StyledWriter writer;
std::string outputConfig = writer.write( data );
//This removes [ at the beginning of entry and also last ] so we can treat it as a Json data
size_t found;
found=outputConfig.find_first_of("[");
int sSize = outputConfig.size();
outputConfig.erase(0,1);
outputConfig.erase((sSize-1),sSize);
reader.parse(outputConfig, value2, false);
cout << value2 << endl;
Json::Value temp;
temp = value2["yt$username"]["yt$display"];
cout << temp << endl;
std::string username = writer.write( temp );
int sSize2 = username.size();
username.erase(0,1);
username.erase((sSize2-3),sSize2);
`
But for some reason [] fix also cuts the data I'm generating, if I print out the data without removing [] I can see all the users but in that case I can't extract temp = value2["yt$username"]["yt$display"];
In JSON, the brackets denote Arrays (nice reference here). You can see this in the online parser, also -- Objects (items with one or more key/value pairs {"key1": "value1", "key2": "value2"}) are denoted with blue +/- signs and Arrays (items inside brackets separated by commas [{arrayItem1}, {arrayItem2}, {arrayItem3}]) are denoted with red +/- signs.
Since entry is an Array, you should be able to iterate through them by doing something like this:
// Assumes value is a Json::Value
Json::Value entries = value["feed"]["entry"];
size_t size = entries.size();
for (size_t index=0; index<size; ++index) {
Json::Value entryNode = entries[index];
cout << entryNode["yt$username"]["yt$display"].asString() << endl;
}
Related
i have this project due however i am unsure of how to parse the data by the word, part of speech and its definition... I know that i should make use of the tab spacing to read it but i have no idea how to implement it. here is an example of the file
Recollection n. The power of recalling ideas to the mind, or the period within which things can be recollected; remembrance; memory; as, an event within my recollection.
Nip n. A pinch with the nails or teeth.
Wodegeld n. A geld, or payment, for wood.
Xiphoid a. Of or pertaining to the xiphoid process; xiphoidian.
NB: Each word and part of speech and definition is one line in a text file.
If you can be sure that the definition will always follow the first period on a line, you could use an implementation like this. But it will break if there are ever more than 2 periods on a single line.
string str = "";
vector<pair<string,string>> v; // <word,definition>
while(getline(fileStream, str, '.')) { // grab line, deliminated '.'
str[str.length() - 1] = ""; // get rid of n, v, etc. from word
v.push_back(make_pair<string,string>(str,"")); // push the word
getline(fileStream, str, '.'); // grab the next part of the line
v.back()->second = str; // push definition into last added element
}
for(auto x : v) { // check your results
cout << "word -> " << x->first << endl;
cout << "definition -> " << x->second << endl << endl;
}
The better solution would be to learn Regular Expressions. It's a complicated topic but absolutely necessary if you want to learn how to parse text efficiently and properly:
http://www.cplusplus.com/reference/regex/
Here is the content of txt file that i've managed read.
X-axis=0-9
y-axis=0-9
location.txt
temp.txt
I'm not sure whether if its possible but after reading the contents of this txt file i'm trying to store just the x and y axis range into 2 variables so that i'll be able to use it for later functions. Any suggestion? And do i need to use vectors? Here is the code for reading of the file.
string configName;
ifstream inFile;
do {
cout << "Please enter config filename: ";
cin >> configName;
inFile.open(configName);
if (inFile.fail()){
cerr << "Error finding file, please re-enter again." << endl;
}
} while (inFile.fail());
string content;
string tempStr;
while (getline(inFile, content)){
if (content[0] && content[1] == '/') continue;
cout << endl << content << endl;
depends on the style of your file, if you are always sure that the style will remain unchanged, u can read the file character by character and implement pattern recognition stuff like
if (tempstr == "y-axis=")
and then convert the appropriate substring to integer using functions like
std::stoi
and store it
I'm going to assume you already have the whole contents of the .txt file in a single string somewhere. In that case, your next task should be to split the string. Personally, yes, I would recommend using vectors. Say you wanted to split that string by newlines. A function like this:
#include <string>
#include <vector>
std::vector<std::string> split(std::string str)
{
std::vector<std::string> ret;
int cur_pos = 0;
int next_delim = str.find("\n");
while (next_delim != -1) {
ret.push_back(str.substr(cur_pos, next_delim - cur_pos));
cur_pos = next_delim + 1;
next_delim = str.find("\n", cur_pos);
}
return ret;
}
Will split an input string by newlines. From there, you can begin parsing the strings in that vector. They key functions you'll want to look at are std::string's substr() and find() methods. A quick google search should get you to the relevant documentation, but here you are, just in case:
http://www.cplusplus.com/reference/string/string/substr/
http://www.cplusplus.com/reference/string/string/find/
Now, say you have the string "X-axis=0-9" in vec[0]. Then, what you can do is do a find for = and then get the substrings before and after that index. The stuff before will be "X-axis" and the stuff after will be "0-9". This will allow you to figure that the "0-9" should be ascribed to whatever "X-axis" is. From there, I think you can figure it out, but I hope this gives you a good idea as to where to start!
std::string::find() can be used to search for a character in a string;
std::string::substr() can be used to extract part of a string into another new sub-string;
std::atoi() can be used to convert a string into an integer.
So then, these three functions will allow you to do some processing on content, specifically: (1) search content for the start/stop delimiters of the first value (= and -) and the second value (- and string::npos), (2) extract them into temporary sub-strings, and then (3) convert the sub-strings to ints. Which is what you want.
C++ newbie here, I'm not sure if my title describes what I am trying to do perfectly, but basically I am trying to output one line of a string array for a certain index of that array.
For example: Say myArray[2] is the 3rd index of a string array, and it holds an entire paragraph, with each sentence separated by a newline character.
contents of myArray[2]: "This is just an example.
This is the 2nd sentence in the paragraph.
This is the 3rd sentence in the paragraph."
I would like to output only the first sentence of the content held in the 3rd index of the string array.
Desired output: This is just an example.
So far I have only been able to output the entire paragraph instead of one sentence, using the basic:
cout << myArray[2] << endl;
But obviously this is not correct. I am assuming the best way to do this is to use the newline character in some way, but I am not sure how to go about that. I was thinking I could maybe copy the array into a new, temporary array which would hold in each index a sentence of the paragraph held in the original array index, but this seems like I am complicating the issue too much.
I have also tried to copy the string array into a vector, but that didn't seem to help my confusion.
You can do something along these lines
size_t end1stSentencePos = myArray[2].find('\n');
std::string firstSentence = end1stSentencePos != std::string::npos?
myArray[2].substr(0,end1stSentencePos) :
myArray[2];
cout << firstSentence << endl;
Here's the reference documentation of std::string::find() and std::string::substr().
Below is a general solution to your problem.
std::string findSentence(
unsigned const stringIndex,
unsigned const sentenceIndex,
std::vector<std::string> const& stringArray,
char const delimiter = '\n')
{
auto result = std::string{ "" };
// If the string index is valid
if(stringIndex < stringArray.size())
{
auto index = unsigned{ 0 };
auto posStart = std::string::size_type{ 0 };
auto posEnd = stringArray[stringIndex].find(delimiter);
// Attempt to find the specified sentence
while((posEnd != std::string::npos) && (index < sentenceIndex))
{
posStart = posEnd + 1;
posEnd = stringArray[stringIndex].find(delimiter, posStart);
index++;
}
// If the sentence was found, retrieve the substring.
if(index == sentenceIndex)
{
result = stringArray[stringIndex].substr(posStart, (posEnd - posStart));
}
}
return result;
}
Where,
stringIndex is the index of the string to search.
sentenceIndex is the index of the sentence to retrieve.
stringArray is your array (I used a vector) that contains all of the strings.
delimiter is the character that specifies the end of a sentence (\n by default).
It is safe in that if an invalid string or sentence index is specified, it returns an empty string.
See a full example here.
From what I could understand in the docs I deducted every xml_node knows it's position in the source text. What I'd like to do is to retrieve LINE and COLUMN for given xml_node<>*:
rapidxml::file<> xmlFile("generators.xml"); // Open file, default template is char
xml_document<> doc; // character type defaults to char
doc.parse<0>(xmlFile.data());; // 0 means default parse flags
xml_node<> *main = doc.first_node(); //Get the main node that contains everything
cout << "My first node is: <" << main->name() << ">\n";
cout << " located at line " << main->?????() << ", column " << main->?????() << "\n";
How should I retrieve those offsets? Could I somehow crawl from the main->name() pointer back to the beginning of the document? But how can I access the document string from xml_document<> doc to compare offsets?
Let's say you parse a simple xml document in a string.
char xml[] = "<hello/><world/>"
doc.parse(xml);
RapidXML will insert null terminators (and maybe make other mods to the "document", so it might look like this now:
char xml[] = "<hello\000\000<world\000\000";
If you than ask for the name() of the 'hello' node, it returns a pointer to the 'h' in your xml array. You can just subtract the base of the array to get an offset.
int offset = node->name() - &xml[0];
Obviously this isn't line and character. To get that, you'd need to count the number of newlines between the offset and the array start. (but maybe do this on a 'clean' version of the xml data, as RapidXML might well mangle newline sequences in the processed version..
AccountNumber Type Amount
15 checking 52.42
23 savings 51.51
11 checking 12.21
is my tab delmited file
i would like to be able to search for rows by the account number. say if i put in 23, i want to get that specific row. how would id do that?
also more advance, if i wanted to change a specific value, say amount 51.51 in account 23. how do i fetch that value and replace it with a new value?
so far im just reading in row by row
string line;
ifstream is("account.txt");
if (is.is_open())
{
while (std::getline(is, line)) // read one line at a time
{
string value;
string parseline;
std::istringstream iss(line);
getline(line, parseline);
cout << parseline << endl; // do something with the value
while (iss >> value) // read one value at at time from the line
{
//cout << line << " "; // do something with the value
}
}
is.close();
}
else
cout << "File cant be opened" << endl;
return 0;
Given that each line is of variable length there is no way to index to particular row without first parsing the entire file.
But I suspect your program will want to manipulate random rows and columns. So I'd start by parsing out the entire file. Put each row into its own data structure in an array, then index that row in the array.
You can use "strtok" to split the input up into rows, and then strtok again to split each row into fields.
If I were to do this, I would first write a few functions that parse the entire file and store the data in an appropriate data structure (such as an array or std::map). Then I would use the data structure for the required operations (such as searching or editing). Finally, I would write the data structure back to a file if there are any modifications.