Input:
[1-st string]Dog
[2-nd string]I love dog
[3-rd string]Dog love me
[4-th string]Love
Output:
[1-st string]Dog
[2-nd string]Love
How can i do such thing in c++ ?>Without using vector.Thx:)
You have a question in the format "No A is within a class B". The algorithm for such problem is
bool wrong = false;
while ( /* there is another A */ )
{
if ( /* check if it is NOT within a class */ )
{
wrong=true;
break;
}
}
if (wrong)
{
// here you know that at least one thing was NOT within a class B
}
else
{
// here you know that every item A was within a class B
}
In your case the "class" is "Strings with no space" and to check if there is space you just use this condition.
Related
I am getting an error that I am having problems fixing as recursion hasn't "sunk in" yet.
It is supposed to go through an array of symbols already placed by the Class OrderManager Object and check if the symbol passed in is already there or not, if it is not there it should allow the trade, otherwise it will block it (multiple orders on the same currency compounds risk)
[Error] '}' - not all control paths return a value.
I believe it is because of the retest portion not having a return value but again I'm still newish to making my own recursive functions. However it may also be because my base and test cases are wrong possibly?
P.S I added (SE) comments in places to clarify language specific things since it is so close to C++.
P.P.S Due to the compiler error, I have no clue if this meets MVRC. Sorry everyone.
bool OrderManager::Check_Risk(const string symbol, uint iter = 0) {
if((iter + 1) != ArraySize(m_symbols) &&
m_trade_restrict != LEVEL_LOW) // Index is one less than Size (SE if
// m_trade_restrict is set to LOW, it
// allows all trades so just break out)
{
if(OrderSelect(OrderManager::Get(m_orders[iter]),
SELECT_BY_TICKET)) // Check the current iterator position
// order (SE OrderSelect() sets an
// external variable in the terminal,
// sort of like an environment var)
{
string t_base = SymbolInfoString(
OrderSymbol(),
SYMBOL_CURRENCY_BASE); // Test base (SE function pulls apart
// the Symbol into two strings
// representing the currency to check
// against)
string t_profit =
SymbolInfoString(OrderSymbol(), SYMBOL_CURRENCY_PROFIT);
string c_base =
SymbolInfoString(symbol, SYMBOL_CURRENCY_BASE); // Current base
// (SE does the same as above but for the passed variable instead):
string c_profit = SymbolInfoString(symbol, SYMBOL_CURRENCY_PROFIT);
// Uses ENUM_LEVELS from Helpers.mqh (SE ENUM of 5 levels: Strict,
// High, Normal, Low, None in that order):
switch(m_trade_restrict) {
case LEVEL_STRICT: {
if(t_base == c_base || t_profit == c_profit) {
return false; // Restrictions won't allow doubling
// orders on any currency
} else
return Check_Risk(symbol, iter++);
};
case LEVEL_NORMAL: {
if(symbol == OrderSymbol()) {
return false; // Restrictions won't allow doubling
// orders on that curr pair
} else
return Check_Risk(symbol, iter++);
};
default: {
// TODO: Logging Manager
// Hardcoded constant global (SE set to LEVEL_NORMAL):
ENB_Trade_Restrictions(default_level);
return Check_Risk(symbol, iter);
}
}
}
} else {
return true;
}
}
So, I must just have been staring at the code for too long but the problem was the if(OrderSelect(...)) on ln 7 did not have a return case if the order was not properly set in the terminal. I will need to polish this but the following code removes the error.
bool OrderManager::Check_Risk(const string symbol, uint iter=0)
{
if((iter + 1) != ArraySize(m_symbols) && m_trade_restrict != LEVEL_LOW) // Index is one less than Size
{
if(OrderSelect(OrderManager::Get(m_orders[iter]), SELECT_BY_TICKET)) //Check the current iterator position order
{
string t_base = SymbolInfoString(OrderSymbol(), SYMBOL_CURRENCY_BASE); //Test base
string t_profit = SymbolInfoString(OrderSymbol(), SYMBOL_CURRENCY_PROFIT);
string c_base = SymbolInfoString(symbol, SYMBOL_CURRENCY_BASE); //Current base
string c_profit = SymbolInfoString(symbol, SYMBOL_CURRENCY_PROFIT);
switch(m_trade_restrict) // Uses ENUM_LEVELS from Helpers.mqh
{
case LEVEL_STRICT :
{
if(t_base == c_base || t_profit == c_profit)
{
return false;
}
else return Check_Risk(symbol, ++iter);
};
case LEVEL_NORMAL :
{
if(symbol == OrderSymbol())
{
return false;
}
else return Check_Risk(symbol, ++iter);
};
default: {
// TODO: Logging Messages
ENB_Trade_Restrictions(default_level); //Hardcoded constant global
return Check_Risk(symbol, iter);
}
}
}
else {return Check_Risk(symbol, ++iter);}
}
else {return true;}
}
In C++, the interface for this file says
*If no soup left returns OUT_OF_SOUP
* If personID not found in my_customers AND numbBowlsSoupLeft>0 then give this person a bowl of soup (return BOWL_OF_SOUP)
* and record it by creating new customer struct using personID, numbBowlsSoup=1 and adding this struct to my_customers, be sure to decrement numbBowlsSoupLeft.
for my implementation, I'm trying to put
int Soupline::getSoup(int personID) {
if (numBowlsSoupLeft == 0) {
return OUT_OF_SOUP;
}
if (!(personID : my_customers) && numbBowlsSoupLeft > 0) {
}
But that second if statement is giving me syntax errros, I just want to know how to check to see if the personID is IN my_customers?
my_customers was created in the soupline interface using:
std::vector<customer> my_customers; // keeps track of customers
First you want to use find() to search a vector.
Second, please handle the case if numbBowlsSoupLeft < 0, because that can be a huge source of problem.
Third, your syntax error is the (personID : my_customers), the : is for iteration.
int Soupline::getSoup(int personID) {
if (numBowlsSoupLeft <= 0) { // handles negative numBowlsSoupLeft
return OUT_OF_SOUP;
}
bool found_customer = false;
for (auto c : my_customers) {
if (personID == c.person_id()) { // This is my guess on how the id is stored in customer class
// Logic to process soup for customer
found_customer = true;
break;
}
}
if (!found_customer) {
// Logic to process non-customer asking for soup?
}
}
Sorry i dunno what is the return integer is supposed to be, so it is not defined in my code example.
I have a while (!Queue.empty()) loop that processes a queue of elements. There are a series of pattern matchers going from highest-priority to lowest-priority order. When a pattern is matched, the corresponding element is removed from the queue, and matching is restarted from the top (so that the highest-priority matchers get a chance to act first).
So right now it looks something like this (a simplified version):
while (!Queue.empty())
{
auto & Element = *Queue.begin();
if (MatchesPatternA(Element)) { // Highest priority, since it's first
// Act on it
// Remove Element from queue
continue;
}
if (MatchesPatternB(Element)) {
// Act on it
// Remove Element from queue
continue;
}
if (MatchesPatternC(Element)) { // Lowest priority, since it's last
// Act on it
// Remove Element from queue
continue;
}
// If we got this far, that means no pattern was matched, so
// Remove Element from queue
}
This works, but I want to refactor this loop in some way to remove the use of the keyword continue.
Why? Because if I want to outsource a pattern matching to an external function, it obviously breaks. E.g.
void ExternalMatching(...)
{
if (MatchesPatternB(Element)) {
// Act on it
// Remove Element from queue
continue; // This won't work here
}
}
while (!Queue.empty())
{
auto & Element = *Queue.begin();
if (MatchesPatternA(Element)) {
// Act on it
// Remove Element from queue
continue;
}
ExternalMatching(...);
if (MatchesPatternC(Element)) {
// Act on it
// Remove Element from queue
continue;
}
// If we got this far, that means no pattern was matched, so
// Remove Element from queue
}
I don't want to have to write repetitive if statements like if (ExternalMatching(...)) { ... continue; }, I'd rather find a cleaner way to express this logic.
This simplified example might make it seem like a good idea to make pattern matching more general rather than having distinct MatchesPatternA, MatchesPatternB, MatchesPatternC, etc. functions. But in my situation the patterns are quite complicated, and I'm not quite ready to generalize them yet. So I want to keep that part as is, separate functions.
Any elegant ideas? Thank you!
If you have access to C++11 I would like to suggest another solution. Basicaly I created a container of handlers and actions that can be adjusted in runtime. It may be a pro or con for your design depending on your requirements. Here it is:
#include <functional>
typedef std::pair<std::function<bool(const ElementType &)>,
std::function<void(ElementType &)> > HandlerData;
typedef std::vector<HandlerData> HandlerList;
HandlerList get_handlers()
{
HandlerList handlers;
handlers.emplace_back([](const ElementType &el){ return MatchesPatternA(el); },
[](ElementType &el){ /* Action */ });
handlers.emplace_back([](const ElementType &el){ return MatchesPatternB(el); },
[](ElementType &el){ /* Action */ });
handlers.emplace_back([](const ElementType &el){ return MatchesPatternC(el); },
[](ElementType &el){ /* Action */ });
return handlers;
}
int main()
{
auto handlers = get_handlers();
while(!Queue.empty()) {
auto &Element = *Queue.begin();
for(auto &h : handlers) {
// check if handler matches the element
if(h.first(Element)) {
// act on element
h.second(Element);
break;
}
}
// remove element
Queue.pop_front();
}
}
I would recommend using a function that does the pattern matching (but does not act on the result) and then a set of functions that act on the different options:
enum EventType {
A, B, C //, D, ...
};
while (!queue.empty()) {
auto & event = queue.front();
EventType e = eventType(event); // Internally does MatchesPattern*
// and returns the match
switch (e) {
case A:
processA(event);
break;
case B:
processB(event);
This way you clearly separate the matching from the processing, the loop is just a simple dispatcher
Consider an interface:
class IMatchPattern
{
public:
virtual bool MatchesPattern(const Element& e) = 0;
};
Then you can organize a container of objects implementing IMatchPattern, to allow for iterative access to each pattern match method.
You can change your ExternalMatching to return bool, indicating that the processing has been done. This way the caller would be able to continue evaluating if necessary:
bool ExternalMatching(...)
{
if (MatchesPatternB(Element) {
// Act on it
// Remove Element from queue
return true;
}
return false;
}
Now you can call it like this:
if (ExternalMatchin1(...)) continue;
if (ExternalMatchin2(...)) continue;
...
if (ExternalMatchingN(...)) continue;
Ok, I ended up rewriting the loop more akin to this.
Huge thanks and credit goes to Yuushi, dasblinkenlight, David RodrÃguez for their help; this answer is based on a combination of their answers.
bool ExternalMatching(...)
{
bool Match;
if ((Match = MatchesPatternX(Element))) {
// Act on it
} else if ((Match = MatchesPatternY(Element))) {
// Act on it
}
return Match;
}
while (!Queue.empty())
{
auto & Element = Queue.front();
if (MatchesPatternA(Element)) { // Highest priority, since it's first
// Act on it
} else if (MatchesPatternB(Element)) {
// Act on it
} else if (ExternalMatching(...)) {
} else if (MatchesPatternC(Element)) { // Lowest priority, since it's last
// Act on it
}
// Remove Element from queue
}
Now, I know there's further room for improvement, see answers of Mateusz Pusz and Michael Sh. However, this is good enough to answer my original question, and it'll do for now. I'll consider improving it in the future.
If you're curious to see the real code (non-simplified version), see here:
https://github.com/shurcooL/Conception/blob/38f731ccc199d5391f46d8fce3cf9a9092f38c65/src/App.cpp#L592
Thanks everyone again!
I would like to suggest a Factory function that would take the Element and create an appropriate handler and return the interface pointer to the handler.
while (!Queue.empty())
{
auto & Element = *Queue.begin();
// get the appropriate handler object pointer e.g.
IPatternHandler *handler = Factory.GetHandler(Element);
handler->handle();
// clean up handler appropriately
}
I have a problem that as i try to remove item from any list in following way i am unable to do that ... why is that so the error is "use of unassigned local variable" where is it is assigned as shown below:
public void RemoveFrmList(int ProdId)
{
int _index;
foreach (Products item in BoughtItems)
{
if (item.ProductID == ProdId)
{
_index = BoughtItems.IndexOf(item);
}
}
BoughtItems.RemoveAt(_index);
}
what can be done to remove this error?
the code inside the if statement does not necessarily occur. Initialize _index to -1 or some "not found" indicating value and the error should go away.
What is BoughtItems ? If it's List<T> just use RemoveAll
public void RemoveFrmList(int ProdId)
{
BoughtItems.RemoveAll( item => item.ProductID == ProdId );
}
Slightly offtopic but why is RemoveFrmLis missing the o? It just hurts readability. Use the full word.
_index is unassigned until you go in the loop. But if BoughtItems has no Product items, you will have a unnassigned variable _index. Or maybe you will never get an item with item.ProductID == ProdID.
So in other words:
int _index;
foreach (Products item in BoughtItems)
{
//Code here is not executed during runtime for reasons stated above.
}
BoughtItems.RemoveAt(_index); //error here because _index was not assigned!
To fix it, you could do something like
int _index = -1;
foreach (...)
{
//...
}
if (_index != -1){
BoughtItems.RemoveAt(_index);
}
else
{
//handle case if needed
}
I want a boolean assigned to a method so then depending on the ouput of that method i know whether to execute a following method or not, but it does not seem to like the way i am doing it.
Code is below
bool ok = (boost::regex_match(str1,string_matcher))
{
DCS_LOG_DEBUG("Correct Number of Passengers");
output.push_back("Correct Number of Passengers\n");
DCS_LOG_DEBUG("2nd loop done 1");
}
else
{
a = st[0];
boost::regex const string_matcher1(splitMask[1]);
boost::trim(a);
if(boost::regex_match(a,string_matcher1))
{
DCS_LOG_DEBUG("Correct format for surnamce");
output.push_back("Correct format for surnamce\n");
DCS_LOG_DEBUG("2nd loop done 4");
}
else
{
DCS_LOG_DEBUG("Invalid format for surname");
output.push_back("Invalid format for surname\n");
DCS_LOG_DEBUG("2nd loop done 5");
}
}
What am i doing wrong there or is it not possible? would be happy for any help :)
You are missing an if:
if (boost::regex_match(str1,string_matcher))
{ ...
OR:
bool ok = boost::regex_match(str1,string_matcher);
if (ok)
{ ...