Here is the github page for Binance C++ API: https://github.com/tensaix2j/binacpp
I am copying a code example from above github project and have a few questions. I pretty much understand everything in the code example but do not understand the last three lines of the code and their precise purpose. Here are the three lines I what to understand.
BinaCPP_websocket::init();
BinaCPP_websocket::connect_endpoint( ws_depth_onData ,"/ws/bnbbtc@depth" );
BinaCPP_websocket::enter_event_loop();
Can somebody explain the meanings and significance of each of the three lines of code above. Do I have to place these lines at the end of the code or I could possibly place them at start of the code.
Here is the full code example from github project on Binance C++ API.
Code: Select all
#include <map>
#include <vector>
#include <string>
#include "binacpp.h"
#include "binacpp_websocket.h"
#include <json/json.h>
using namespace std;
map < string, map <double,double> > depthCache;
int lastUpdateId;
//------------------------------
void print_depthCache() {
map < string, map <double,double> >::iterator it_i;
for ( it_i = depthCache.begin() ; it_i != depthCache.end() ; it_i++ ) {
string bid_or_ask = (*it_i).first ;
cout << bid_or_ask << endl ;
cout << "Price Qty" << endl ;
map <double,double>::reverse_iterator it_j;
for ( it_j = depthCache[bid_or_ask].rbegin() ; it_j != depthCache[bid_or_ask].rend() ; it_j++ ) {
double price = (*it_j).first;
double qty = (*it_j).second;
printf("%.08f %.08f\n", price, qty );
}
}
}
//-------------
int ws_depth_onData( Json::Value &json_result ) {
int i;
int new_updateId = json_result["u"].asInt();
if ( new_updateId > lastUpdateId ) {
for ( i = 0 ; i < json_result["b"].size() ; i++ ) {
double price = atof( json_result["b"][i][0].asString().c_str());
double qty = atof( json_result["b"][i][1].asString().c_str());
if ( qty == 0.0 ) {
depthCache["bids"].erase(price);
} else {
depthCache["bids"][price] = qty;
}
}
for ( i = 0 ; i < json_result["a"].size() ; i++ ) {
double price = atof( json_result["a"][i][0].asString().c_str());
double qty = atof( json_result["a"][i][1].asString().c_str());
if ( qty == 0.0 ) {
depthCache["asks"].erase(price);
} else {
depthCache["asks"][price] = qty;
}
}
lastUpdateId = new_updateId;
}
print_depthCache();
}
//---------------------------
/*
To compile, type
make example_depthCache
*/
//--------------------------
int main() {
Json::Value result;
long recvWindow = 10000;
// Market Depth
int i;
string symbol = "BNBBTC";
BinaCPP::get_depth( symbol.c_str(), 20, result ) ;
// Initialize the lastUpdateId
lastUpdateId = result["lastUpdateId"].asInt();
for ( int i = 0 ; i < result["asks"].size(); i++ ) {
double price = atof( result["asks"][i][0].asString().c_str() );
double qty = atof( result["asks"][i][1].asString().c_str() );
depthCache["asks"][price] = qty;
}
for ( int i = 0 ; i < result["bids"].size() ; i++ ) {
double price = atof( result["bids"][i][0].asString().c_str() );
double qty = atof( result["bids"][i][1].asString().c_str() );
depthCache["bids"][price] = qty;
}
print_depthCache();
BinaCPP_websocket::init();
BinaCPP_websocket::connect_endpoint( ws_depth_onData ,"/ws/bnbbtc@depth" );
BinaCPP_websocket::enter_event_loop();
}