Searching a string of numbers

[Callum5042]

I have a vector that holds a bunch of numbers for objects. But say you got the numbers "2, 3, 4, 6", and say when I used the function to create them, I created them under string "Create".

How would I be able to put this string in to find the amount of number related to the string. Also, it is not a set number. How would I go with doing this?

[strongdrink]

What about a stringstream?

std::stringstream numStream;

for (int i : someVector) {
  numStream << i;
}

std::string numString = numStream.str();

[Need4Sleep]

The most simple method would be to use a for loop to run through each element of a string, since a string is just an array of chars.

for(int i = 0; i < StrLen;i++)
{
   if String[i] == SearchItem
       //do stuff
}

OR you if you want efficiency use quicksort followed by a binarysearch to find your number.

Hope this helps

[Callum5042]

I'm not searching through the character of the string though, I'm at college but I'll post the code of how it is created atm so you understand what I mean a bit more.

But let say:

int 1, 3, 4, 7, 9 are created under the string "First"
int 2, 5, 6, 8, 10 are created under the string "Second"

Then let say I can use "First" to move all the numbers under it.

I was thinking of maybe a multimap, but not too sure if it would work.

[JLBorges]

> I was thinking of maybe a multimap, but not too sure if it would work

It would work.
Though you might find that it is more convenient to use a std::map< std::string, std::vector<int> >

std::map< std::string, std::vector<int> > look_up ;
look_up["First"] = { 1, 4, 6, 12, 99 } ;
look_up["Second"] = { 26, 17, 4, 48 } ;

look_up["Third"].push_back(50) ; // add 50 under key "Third"
look_up["Second"].push_back(19) ; // add 19 under key "Second"

// print out each number under key "Second"
for( int i : look_up["Second"] ) std::cout << i << ' ' ;

[Callum5042]

Hmm not sure if it working yet, but I'm using this

std::map<std::string, std::vector<Object>> ObjectName;

Then this when I want to create a new object

void Engine::CreateObject(std::string name, std::string path, int x, int y)
{
	Object Create;
	ObjectName[name].push_back(Create);
	ObjectName[name][ObjectAmount].Init(path, ObjectAmount, x, y);
	ObjectAmount++;
}

But how would I go with displaying all of the Objects within the map?

[JLBorges]

> ObjectAmount++;

A std::vector<> keeps track of the number of elements in it; ObjectAmount is redundant.
http://www.cplusplus.com/reference/stl/vector/size/


> how would I go with displaying all of the Objects within the map?

// C++11
for( auto& pair : ObjectName ) // for each key-data pair in the map
{
    const auto& name = pair.first ; // key (string)
    for( auto& obj : pair.second ) // for each Object in the vector
    {
        // do something with obj
    }
}

// also C++98
typedef std::map<std::string, std::vector<Object> >::iterator iterator ;
for( iterator iter = ObjectName.begin() ; iter != ObjectName.end() ; ++iter )
{
    const std::string& name = iter->first ; // key (string)
    std::vector<Object>& vec = iter->second ; // data (vector)
    for( std::size_t i = 0 ; i < vec.size() ; ++i ) // for each Object in the vector
    {
        Object& obj = vec[i] ;
        // do something with obj
    }
}

[Callum5042]

That works fine

// C++11
for( auto& pair : ObjectName ) // for each key-data pair in the map
{
    const auto& name = pair.first ; // key (string)
    for( auto& obj : pair.second ) // for each Object in the vector
    {
        // do something with obj
    }
}

But I see what I'm doing wrong, I need it to create a new map everytime I need a different name.

engine->CreateObject("Main", "path", 256, 256);
engine->CreateObject("Testing", "path", 128, 256);

Now only main will be created, but I want to be able to create others when I call that function. And ObjectAmount, is for setting the amount.

If you see what I mean.

[JLBorges]

> If you see what I mean.

No, I'm afraid I don't.

[Callum5042]

I'll try to explain, I'm writing a .lib file for a simple game engine.

To create a new object I use this code engine->CreateObject("Main", "path", 128, 128);

With main being the name of the object, path being the file path for the picture and 128 being x and y.


So say when we press 'x' we do this

if (KeyDown(xKey))
{
	engine->CreateObject("bullet", "path", 128, 128);
}

And if we press 'c' we do this

if (KeyDown(cKey))
{
	engine->CreateObject("missile", "path", 256, 256);
}

The CreateObject function

void Engine::CreateObject(std::string name, std::string path, int x, int y)
{
	Object Create;
	ObjectName[name].push_back(Create);
	ObjectName[name][ObjectAmount].Init(path, ObjectAmount, x, y);
	ObjectAmount++;
}

At the moment, I can only create one of them, but I create more then one under the same name. So I could only do:
engine->CreateObject("bullet", "path", 256, 256);
but not
engine->CreateObject("missile", "path", 128, 128);

So my question is, how would I be able to call more than just one of them?

Hopefully this makes it a bit clearer.

[JLBorges]

Get rid of that ObjectAmount; it is completely useless.

This is an error: ObjectName[name][ObjectAmount].Init(path, ObjectAmount, x, y);

ObjectAmount holds the total number of objects under all names; it is an invalid index into the vector under a particular name.

Instead, do something like this:

#include <map>
#include <vector>

struct Object
{
    Object( const std::string& path, int x, int y ) : path(path), x(x), y(y) {}
    void Init( /* ... */ ) { /* ... */ }
    // ...

    private:
        std::string path ;
        int x ;
        int y ;
};

struct Engine
{
    // ...

    void CreateObject( const std::string& name, const std::string& path, int x, int y )
    {
        ObjectName[name].emplace_back( path, x, y ) ; // C++11
        // or: ObjectName[name].push_back( Object( path, x, y ) ) ; // C++98

        ObjectName[name].back().Init(  /* ... */ ) ;

        // or alternatively:
        // std::vector<Object>& vec = ObjectName[name] ;
        // vec[ vec.size() - 1 ].Init(  /* ... */ ) ;
    }

    private: std::map< std::string, std::vector<Object> > ObjectName ;
    // ...
};

int main()
{
    Engine engine ;
    engine.CreateObject( "bullet", "abc/def/bullet.png", 100, 70 ) ;
    engine.CreateObject( "missile", "abc/def/missile.png", 50, 120 ) ;
    engine.CreateObject( "bullet", "abc/def/bullet.png", 0, 45 ) ;
    engine.CreateObject( "missile", "abc/def/missile.png", 96, 128 ) ;
    // etc.
}

[Callum5042]

Thanks, it working good now :D.

You're quite the programmer :),

just one more thing.

This creates the bullet
engine->CreateObject("Bullet","Path",engine->object["Main"].back().x,engine->object["Main"].back().y);

But say I want to make them all move at -y;

Now I can do this using a loop

for (unsigned int i = 0; i < engine->object["Bullet"].size(); ++i)
{
	engine->object["Bullet"][i].y -= 2;
}

Is there a easier way to do this?, something like.

engine->object["Bullet"][ALL].y -= 2;

Thanks

[JLBorges]

> Is there a easier way to do this?

Not really. A range based for loop would make the code cleaner:

for( auto& obj : engine->object["Bullet"] ) obj.y -= 2 ;

[Callum5042]

Alright, cheers.