Yes, in fact, [`std::map::erase()`](http://en.cppreference.com/w/cpp/container/map/erase) returns a size_type which indicates the number of keys erased. Thus it returns 0 for nothing erased and 1 for something erased for a map.

This is perfectly fine, mymap.erase(&#39;D&#39;) will return 0 in this case.

See [http://www.cplusplus.com/reference/stl/map/erase.html][1]


  [1]: http://www.cplusplus.com/reference/stl/map/erase.html

I&#39;m putting a large codebase into Team Foundation Server. I would like the build process to create a &quot;ready to deploy&quot; build of our projects.

The normal way we&#39;ve been doing this is to have each project&#39;s output be in its own folder. So, for example, we wind up with something like

    C:\project1\
                assembly1.dll
                assembly2.dll
                project1.exe
                project1.exe.config
    C:\project2\
                assembly2.dll
                assembly3.dll
                project2.exe
                project2.exe.config
    C:\project3\
                assembly1.dll
                assembly3.dll
                project3.exe
                project3.exe.config

Which is the way we like it.

TFS, though, seems to want to stick everything in the same directory.

    C:\output\
              assembly1.dll
              assembly2.dll
              assembly3.dll
              project1.exe
              project1.exe.config
              project2.exe
              project2.exe.config
              project3.exe
              project3.exe.config

which, although it saves some amount of disk space (the assemblies are only there one time each) is not how we want it. 

What&#39;s the best way to specify where TFS/MSBuild should put the output files? Do I need to edit sln/csproj files individually to achieve this or can I do it in the TFSBuild.proj file? (i.e., in a MSBuild-specific file)

What&#39;s the best way to get TFS to output each project to its own directory?

I need to get unmanaged Windows C++ clients to talk to a WCF service. C++ clients could be running on Win2000 and later. I have a control over both WCF service and which C++ API is being used. Since it&#39;s for a proprietary application, it is preferable to use Microsoft stuff where possible, definitely not GNU licensed APIs. Those of you who have it working, can you share a step-by-step process how to make it working?

I have researched following options so far:

- WWSAPI - not good, will not work on Win 2000 clients.
- ATL Server, used [following guide][1] as a reference. I followed the steps outlined (remove policy refs and flatten WSDL), however the resulting WSDL is still not usable by sproxy

Any more ideas? Please answer only if you actually have it working yourself.

***Edit1***: I apologize for anyone who I might have confused: what I was looking for was a way to call WCF service from client(s) where no .NET framework is installed, so using .NET-based helper library is not an option, it must be pure unmanaged C++

  [1]: http://icoder.wordpress.com/2007/07/25/consuming-a-wcf-service-with-an-unmanaged-c-client-with-credential-passing/

Create WCF service for unmanaged C++ clients

Regarding the C++ STL map, erasing by key:-

     size_type map::erase ( const key_type&amp; x );

Is it legal to erase a non-existing key? i.e. is the snippet below ok?

    map&lt;char,int&gt; mymap;
    mymap[&#39;c&#39;]=30;
    mymap.erase(&#39;c&#39;);
    mymap.erase(&#39;c&#39;);
    mymap.erase(&#39;D&#39;);

Cheers


C++ STL map::erase a non-existing key

Regarding the C++ STL map, erasing by key:-
<pre><code class="hljs language-arduino"> size_type map::erase ( const key_type&#x26; x );
</code></pre>
Is it legal to erase a non-existing key? i.e. is the snippet below ok?
<pre><code class="hljs language-arduino">map&#x3C;char,int> mymap;
mymap['c']=30;
mymap.erase('c');
mymap.erase('c');
mymap.erase('D');
</code></pre>
Cheers

Alright, I think we all agree that what happens with the following code is undefined, depending on what is passed,

    void deleteForMe(int* pointer)
    {
         delete[] pointer;
    }

The pointer could be all sorts of different things, and so performing an unconditional `delete[]` on it is undefined. However, let&#39;s assume that we are indeed passing an array pointer,

    int main()
    {
         int* arr = new int[5];
         deleteForMe(arr);
         return 0;
    }

My question is, in this case where the pointer __is__ an array, who is it that knows this? I mean, from the language/compiler&#39;s point of view, it has no idea whether or not `arr` is an array pointer versus a pointer to a single int. Heck, it doesn&#39;t even know whether `arr` was dynamically created. Yet, if I do the following instead,

    int main()
    {
         int* num = new int(1);
         deleteForMe(num);
         return 0;
    }

The OS is smart enough to only delete one int and not go on some type of &#39;killing spree&#39; by deleting the rest of the memory beyond that point (contrast that with `strlen` and a non-`\0`-terminated string -- it will keep going until it hits 0).

So whose job is it to remember these things? Does the OS keep some type of record in the background? (I mean, I realise that I started this post by saying that what happens is undefined, but the fact is, the &#39;killing spree&#39; scenario doesn&#39;t happen, so therefore in the practical world _someone_ is remembering.)


How does delete[] know it&#39;s an array?

I always wondered why automatic setting of the pointer to NULL after *delete* is not part of the standard. If this gets taken care of then many of the crashes due to an invalid pointer would not occur. But having said that I can think of couple of reasons why the standard would have restricted this:

&gt;    1. Performance:
&gt;
&gt;       An additional instruction could slow down the `delete` performance. 
&gt;    
&gt;    2. Could it be because of `const` pointers. 
&gt;
&gt;       Then again standard could have done something for this special case I guess. 

Does anyone know exact reasons for not allowing this? 




Why doesn&#39;t delete set the pointer to NULL?

I am using std::queue for implementing JobQueue class. ( Basically this class process each job in FIFO manner).
In one scenario, I want to clear the queue in one shot( delete all jobs from the queue).
I don&#39;t see any clear method available in std::queue class.

How do I efficiently implement the clear method for JobQueue class ?

I have one simple solution of popping in a loop but I am looking for better ways.


 
    //Clears the job queue
    void JobQueue ::clearJobs()
     {
      // I want to avoid pop in a loop
        while (!m_Queue.empty())
        {
            m_Queue.pop();
        }
    }





How do I clear the std::queue efficiently?

I ran across `enable_shared_from_this` while reading the Boost.Asio examples and after reading the documentation I am still lost for how this should correctly be used.  Can someone please give me an example and explanation of when using this class makes sense.

What is the usefulness of `enable_shared_from_this`?

Could you C++ developers please give us a good description of what RAII is, why it is important, and whether or not it might have any relevance to other languages?

I *do* know a little bit. I believe it stands for &quot;Resource Acquisition is Initialization&quot;. However, that name doesn&#39;t jive with my (possibly incorrect) understanding of what RAII is: I get the impression that RAII is a way of initializing objects on the stack such that, when those variables go out of scope, the destructors will automatically be called causing the resources to be cleaned up.

So why isn&#39;t that called &quot;using the stack to trigger cleanup&quot; (UTSTTC:)? How do you get from there to &quot;RAII&quot;?

And how can you make something on the stack that will cause the cleanup of something that lives on the heap? Also, are there cases where you can&#39;t use RAII? Do you ever find yourself wishing for garbage collection? At least a garbage collector you could use for some objects while letting others be managed?

Thanks.

Understanding the meaning of the term and the concept - RAII (Resource Acquisition is Initialization)

I have always wondered why you cannot use locally defined classes as predicates to STL algorithms. 

In the question: [Approaching STL algorithms, lambda, local classes and other approaches][1], BubbaT mentions says that &#39;*Since the C++ standard forbids local types to be used as arguments*&#39;

Example code:

    int main() {
       int array[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
       std::vector&lt;int&gt; v( array, array+10 );
    
       struct even : public std::unary_function&lt;int,bool&gt;
       {
          bool operator()( int x ) { return !( x % 2 ); }
       };
       std::remove_if( v.begin(), v.end(), even() ); // error
    }

Does anyone know where in the standard is the restriction? What is the rationale for disallowing local types?

  [1]: https://stackoverflow.com/questions/256557/approaching-stl-algorithms-lambda-local-classes-and-other-approaches

---
**EDIT**: Since C++11, it is legal to use a local type as a template argument.

Using local classes with STL algorithms

I have a `std::vector` with `n` elements. Now I need to pass a pointer to a vector that has the last `n-1` elements to a function.

For example, my `vector&lt;int&gt; foo` contains `(5,2,6,87,251)`. A function takes `vector&lt;int&gt;*` and I want to pass it a pointer to `(2,6,87,251)`.

Can I just (safely) take the iterator `++foo.begin()`, convert it to a pointer and pass that to the function? Or use `&amp;foo[1]`?

**UPDATE:** People suggest that I change my function to take an iterator rather than a pointer. That seems not possible in my situation, since the function I mentioned is the `find` function of `unordered_set&lt;std::vector*&gt;`. So in that case, is copying the `n-1` elements from `foo` into a new vector and calling `find` with a pointer to that the only option? Very inefficient! It&#39;s like Shlemiel the painter, especially since i have to query many subsets: the last `n-1`, then `n-2`, etc. elements and see if they are in the `unordered_set`.

Convert iterator to pointer?

As an extension to this question [Are `const_iterators` faster?][1], I have another question on `const_iterators`. How to remove constness of a `const_iterator`? 
Though iterators are generalised form of pointers but still `const_iterator` and `iterator`s are two different things. Hence, I  believe, I also cannot use `const_cast&lt;&gt;` to covert from `const_iterator` to `iterator`s.

One approach could be that you define an iterator which moves &#39;til the element to which `const_iterator` points. But this looks to be a linear time algorithm.

Any idea on what is the best way to achieve this?


  [1]: https://stackoverflow.com/questions/755347/are-constiterators-faster

How to remove constness of const_iterator?

Working my way through Effective STL at the moment. Item 5 suggests that it&#39;s usually preferable to use range member functions to their single element counterparts. I currently wish to copy all the values in a map (i.e. - I don&#39;t need the keys) to a vector.

What is the cleanest way to do this?

Copy map values to vector in STL

I was trying to erase a range of elements from map based on particular condition. How do I do it using STL algorithms?

Initially I thought of using `remove_if` but it is not possible as remove_if does not work for associative container.

Is there any &quot;remove_if&quot; equivalent algorithm which works for map ?

As a simple option, I thought of looping through the map and erase. But is looping through the map and erasing a safe option?(as iterators get invalid after erase)

I used following example:

    bool predicate(const std::pair&lt;int,std::string&gt;&amp; x)
    {
    	return x.first &gt; 2;
    }
    
    int main(void) 
    {
    	
    	std::map&lt;int, std::string&gt; aMap;
    
    	aMap[2] = &quot;two&quot;;
    	aMap[3] = &quot;three&quot;;
    	aMap[4] = &quot;four&quot;;
    	aMap[5] = &quot;five&quot;;
    	aMap[6] = &quot;six&quot;;
    
    //      does not work, an error
    //	std::remove_if(aMap.begin(), aMap.end(), predicate);
    
    	std::map&lt;int, std::string&gt;::iterator iter = aMap.begin();
    	std::map&lt;int, std::string&gt;::iterator endIter = aMap.end();
    
    	for(; iter != endIter; ++iter)
    	{
    			if(Some Condition)
    			{
                                // is it safe ?
    				aMap.erase(iter++);
    			}
    	}
    
    	return 0;
    }



remove_if equivalent for std::map

How do I write in YAML a dictionary (map) where one key has the empty string as its value?

YAML: dictionary with empty value

What are the reasons behind the decision to not have a fully generic get method 
in the interface of &lt;a href=&quot;http://java.sun.com/javase/6/docs/api/java/util/Map.html#get(java.lang.Object)&quot;&gt;`java.util.Map&lt;K, V&gt;`&lt;/a&gt;.

To clarify the question, the signature of the method is 

`V get(Object key)`

instead of 

`V get(K key)`

and I&#39;m wondering why (same thing for `remove, containsKey, containsValue`).

What are the reasons why Map.get(Object key) is not (fully) generic

What is the best way to convert a `Map&lt;key,value&gt;` to a `List&lt;value&gt;`? Just iterate over all values and insert them in a list or am I overlooking something?

How to convert a Map to List in Java?

I&#39;m facing a problem that seems to have no straighforward solution.

I&#39;m using `java.util.Map`, and I want to update the value in a Key-Value pair.

Right now, I&#39;m doing it lik this:

    private Map&lt;String,int&gt; table = new HashMap&lt;String,int&gt;();
    public void update(String key, int val) {
        if( !table.containsKey(key) ) return;
        Entry&lt;String,int&gt; entry;
        for( entry : table.entrySet() ) {
            if( entry.getKey().equals(key) ) {
                entry.setValue(val);
                break;
            }
        }
    }

So is there any method so that I can get the required `Entry` object without having to iterate through the entire `Map`? Or is there some way to update the entry&#39;s value in place? Some method in `Map` like `setValue(String key, int val)`?

jrh

Updating a java map entry

What are the differences between PRIMARY, UNIQUE, INDEX and FULLTEXT when creating MySQL tables?

How would I use them?

Differences between INDEX, PRIMARY, UNIQUE, FULLTEXT in MySQL?

I have a Perl script that is counting the number of occurrences of various strings in a text file. I want to be able to check if a certain string is not yet a key in the hash. Is there a better way of doing this altogether?

Here is what I am doing:

    foreach $line (@lines){
        if(($line =~ m|my regex|) )
        {
            $string = $1;
            if ($string is not a key in %strings) # &quot;strings&quot; is an associative array
            {
                $strings{$string} = 1;
            }
            else
            {
                $n = ($strings{$string});
                $strings{$string} = $n +1;
            }
        }
    }


How can I see if a Perl hash already has a certain key?

Do you need to explicitly create an index, or is it implicit when defining the primary key?  Is the answer the same for MyISAM and InnoDB?

Is the primary key automatically indexed in MySQL?

I have a `std::map` that I&#39;m using to store values for x and y coordinates. My data is very sparse, so I don&#39;t want to use arrays or vectors, which would result in a massive waste of memory. My data ranges from -250000 to 250000, but I&#39;ll only have a few thousand points at the most.

Currently I&#39;m creating a `std::string` with the two coordinates (i.e. `&quot;12x45&quot;`) and using it as a key. This doesn&#39;t seem like the best way to do it.

My other thoughts were to use an int64 and shove the two int32s into it and use it as a key.

Or to use a class with the two coordinates. What are the requirements on a class that is to be used as the key?

What is the best way to do this? I&#39;d rather not use a map of maps.

What is the best way to use two keys with a std::map?

I am building a custom shopping cart where CC numbers and Exp date will be stored in a database until processing (then deleted). I need to encrypt this data (obviously).

I want to use the RSACryptoServiceProvider class.

Here is my code to create my keys.

    public static void AssignNewKey(){
        const int PROVIDER_RSA_FULL = 1;
        const string CONTAINER_NAME = &quot;KeyContainer&quot;;
        CspParameters cspParams;
        cspParams = new CspParameters(PROVIDER_RSA_FULL);
        cspParams.KeyContainerName = CONTAINER_NAME;
        cspParams.Flags = CspProviderFlags.UseMachineKeyStore;
        cspParams.ProviderName = &quot;Microsoft Strong Cryptographic Provider&quot;;
        rsa = new RSACryptoServiceProvider(cspParams);

        string publicPrivateKeyXML = rsa.ToXmlString(true);
        string publicOnlyKeyXML = rsa.ToXmlString(false);
        // do stuff with keys...
    }


Now the plan is to store the private key xml on a USB drive attached to the managers key chain.


Whenever a manager leaves the company I want to be able to generate new public and private keys (and re-encrypt all currently stored CC numbers with the new public key).

My problem is that the keys generated by this code are always the same. How would I generate a unique set of keys every time?


&lt;strong&gt;UPDATE.&lt;/strong&gt; My test code is below.:&lt;br /&gt;
&lt;em&gt;note: the &quot;privatekey&quot; parameter here is the original private key. In order for the keys to be changed I need to verify that the private key is valid.&lt;/em&gt;

In Default.aspx.cs

    public void DownloadNewPrivateKey_Click(object sender, EventArgs e)
    {
        StreamReader reader = new StreamReader(fileUpload.FileContent);
        string privateKey = reader.ReadToEnd();
        Response.Clear();
        Response.ContentType = &quot;text/xml&quot;;
        Response.End();
        Response.Write(ChangeKeysAndReturnNewPrivateKey(privateKey));
    }

In Crytpography.cs:

    public static privateKey;
    public static publicKey;
    public static RSACryptoServiceProvider rsa;

    public static string ChangeKeysAndReturnNewPrivateKey(string _privatekey)
    {
            
        string testData = &quot;TestData&quot;;
        string testSalt = &quot;salt&quot;;
        // encrypt the test data using the exisiting public key...
        string encryptedTestData = EncryptData(testData, testSalt);
        try
        {
            // try to decrypt the test data using the _privatekey provided by user...
            string decryptTestData = DecryptData(encryptedTestData, _privatekey, testSalt);
            // if the data is successfully decrypted assign new keys...
            if (decryptTestData == testData)
            {
                AssignNewKey();
                // &quot;AssignNewKey()&quot; should set &quot;privateKey&quot; to the newly created private key...
                return privateKey;
            }
            else
            {
                return string.Empty;
            }
        }
        catch (Exception ex)
        {
            return string.Empty;
        }
    }
    public static void AssignParameter(){
        const int PROVIDER_RSA_FULL = 1;
        const string CONTAINER_NAME = &quot;KeyContainer&quot;;
        CspParameters cspParams;
        cspParams = new CspParameters(PROVIDER_RSA_FULL);
        cspParams.KeyContainerName = CONTAINER_NAME;
        cspParams.Flags = CspProviderFlags.UseMachineKeyStore;
        cspParams.ProviderName = &quot;Microsoft Strong Cryptographic Provider&quot;;
        rsa = new RSACryptoServiceProvider(cspParams);
    }
    public static void AssignNewKey()
    {
        AssignParameter();
        
        using (SqlConnection myConn = new SqlConnection(Utilities.ConnectionString))
        {
            SqlCommand myCmd = myConn.CreateCommand();

            string publicPrivateKeyXML = rsa.ToXmlString(true);
            privateKey = publicPrivateKeyXML; // sets the public variable privateKey to the new private key.

            string publicOnlyKeyXML = rsa.ToXmlString(false);
            publicKey = publicOnlyKeyXML; // sets the public variable publicKey to the new public key.

            myCmd.CommandText = &quot;UPDATE Settings SET PublicKey = @PublicKey&quot;;
            myCmd.Parameters.AddWithValue(&quot;@PublicKey&quot;, publicOnlyKeyXML);
            myConn.Open();

            myComm.ExecuteScalar();
        }
    }
    public static string EncryptData(string data2Encrypt, string salt)
    {
        AssignParameter();

        using (SqlConnection myConn = new SqlConnection(Utilities.ConnectionString))
        {
            SqlCommand myCmd = myConn.CreateCommand();

            myCmd.CommandText = &quot;SELECT TOP 1 PublicKey FROM Settings&quot;;

            myConn.Open();

            using (SqlDataReader sdr = myCmd.ExecuteReader())
            {
                if (sdr.HasRows)
                {
                    DataTable dt = new DataTable();
                    dt.Load(sdr);
                    rsa.FromXmlString(dt.Rows[0][&quot;PublicKey&quot;].ToString());
                }
            }
        }

        //read plaintext, encrypt it to ciphertext
        byte[] plainbytes = System.Text.Encoding.UTF8.GetBytes(data2Encrypt + salt);
        byte[] cipherbytes = rsa.Encrypt(plainbytes, false);
        return Convert.ToBase64String(cipherbytes);
    }
    public static string DecryptData(string data2Decrypt, string privatekey, string salt)
    {
        AssignParameter();

        byte[] getpassword = Convert.FromBase64String(data2Decrypt);

        string publicPrivateKeyXML = privatekey;
        rsa.FromXmlString(publicPrivateKeyXML);
 
        //read ciphertext, decrypt it to plaintext
        byte[] plain = rsa.Decrypt(getpassword, false);
        string dataAndSalt = System.Text.Encoding.UTF8.GetString(plain);
        return dataAndSalt.Substring(0, dataAndSalt.Length - salt.Length);
    }

How to Generate Unique Public and Private Key via RSA

I have a std::vector&amp;lt;int&gt;, and I want to delete the n&#39;th element. How do I do that?

    std::vector&lt;int&gt; vec;

    vec.push_back(6);
    vec.push_back(-17);
    vec.push_back(12);

    vec.erase(???);




How do I erase an element from std::vector&lt;&gt; by index?

How can I erase the current printed console line in C? I am working on a Linux system. For example - 

    printf(&quot;hello&quot;);
    printf(&quot;bye&quot;);

I want to print bye on the same line in place of hello.

Erase the current printed console line

    vector&lt;int&gt; myVector;

and lets say the values in the vector are this (in this order):

    5 9 2 8 0 7

If I wanted to erase the element that contains the value of &quot;8&quot;, I think I would do this:

    myVector.erase(myVector.begin()+4);

Because that would erase the 4th element. But is there any way to erase an element based off of the value &quot;8&quot;?  Like:

    myVector.eraseElementWhoseValueIs(8);

Or do I simply just need to iterate through all the vector elements and test their values?



C++ Erase vector element by value rather than by position?

Whats a simple way to delete the last two characters of a string?

How to delete &quot;px&quot; from 245px

I know that there are similar questions to this one, but I didn’t manage to find the way on my code by their aid. I want merely to delete/remove an element of a vector by checking an attribute of this element inside a loop. How can I do that? I tried the following code but I receive the vague message of error:

&#39;operator =&#39; function is unavailable in &#39;Player’.

     for (vector&lt;Player&gt;::iterator it = allPlayers.begin(); it != allPlayers.end(); it++)
     {
         if(it-&gt;getpMoney()&lt;=0) 
             it = allPlayers.erase(it);
         else 
             ++it;
     }


What should I do?   

**Update:** Do you think that the question https://stackoverflow.com/questions/2677770/vectorerase-with-pointer-member pertains to the same problem? Do I need hence an assignment operator? Why? 


Content Type	Original Author	Original Content on Stackoverflow
Question	fuad	View Question on Stackoverflow
Solution 1 - C++	rlbond	View Answer on Stackoverflow
Solution 2 - C++	brian-brazil	View Answer on Stackoverflow

C++ STL map::erase a non-existing key

C++ Problem Overview

C++ Solutions

Solution 1 - C++

Solution 2 - C++

Create WCF service for unmanaged C++ clients

What's the best way to get TFS to output each project to its own directory?

Attributions