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1. Top results related to what are the function of dictionary in computer

   • What are the interest of returning DictRow instead of simple dictionary in Psycopg2?

     Top Answer

     Answered Sep 14, 2017 · 0 votes

     From the linked documentation:

     The records still support indexing as the original tuple:

     >>> rec[2] "abc'def"`-

     So DictRow supports both indexing into a row tuple (when you give it an int or a slice) and by-column-name access.

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     1/5

   • What are the benefits of function pointers in C?

     Top Answer

     Answered Jul 19, 2017 · 3 votes

     • Same as regular typdefs, incredibly useful for 2 and 4. Instead of typing the whole thing, you can now use myFuncDef
     • A function declaration for a function that recieves a function pointer. A function that takes a function pointer of 1. would thus look int add2to3(myFuncDef functionPtr);
     • -
     • A function that takes an int and (probably based on that) returns you a function pointer. Using the typedef it would have looked like myFuncDef functionFactory(int n);

     Without typedefs these chains of pointers to pointers could get incredibly long as can be seen in this question: C syntax for functions returning function pointers

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     2/5

   • What are the Types of Linking Function in Angular ?

     When working with Angular directives, understanding the concept and types of linking functions is essential. Linking functions are a crucial part of the directive’s lifecycle, allowing developers to interact with the directive’s DOM element and scope. In this article, we will explore the different types of linking functions in Angular and how to use them effectively.

     Linking Function

     The Linking function in Angular provides a bridge between the directive and the template’s DOM elements. They play a significant role during the linking phase of the directive’s lifecycle. The linking function executes once the directive has been compiled and linked to the template, giving developers the ability to manipulate DOM elements, handle events, and update scope data.

     In Angular, there are two types of linking functions:

     Pre-linking Function 

     The pre-linking function executes before the child elements are linked to the parent directive. It allows developers to perform tasks before Angular compiles and links the child elements.

     Syntax:

     function preLinkingFunction(scope: ng.IScope, element: JQLite, attrs: ng.IAttributes):void { // Your code here}

     Post-linking Function 

     The post-linking function executes after the child elements are linked to the parent directive. It enables developers...

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     3/5

   • What are the attributes of 'urlretrieve' function in Python?

     Top Answer

     Answered Nov 04, 2015 · 0 votes

     If we take a look at the official Python documentation for urllib.urlretrieve

     , we get a nice explanation:

     Copy a network object denoted by a URL to a local file, if necessary. If the URL points to a local file, or a valid cached copy of the object exists, the object is not copied. Return a tuple (filename, headers) where filename is the local file name under which the object can be found, and headers is whatever the info() method of the object returned by urlopen() returned (for a remote object, possibly cached). Exceptions are the same as for urlopen().

     The second argument, if present, specifies the file location to copy to (if absent, the location will be a tempfile with a generated name). The third argument, if present, is a hook function that will be called once on establishment of the network connection and once after each block read thereafter. The hook will be passed three arguments; a count of blocks transferred so far, a block size in bytes, and the total size of the file. The third argument may be -1 on older FTP servers which do not return a file size in response to a retrieval request.

     If the url uses the http: scheme identifier, the optional data argument may be given to specify a POST request (normally the request type is GET). The data argument must in standard application/x-www-form-urlencoded format; see the urlencode() function below.

     Changed in version 2.5: urlretrieve() will raise ContentTooShortError

     when it detects that the amount of data available was less than the expected amount (which is the size reported by a Content-Length header). This can occur, for example, when the download is interrupted.

     The Content-Length is treated as a lower bound: if there’s more data to read, urlretrieve() reads more data, but if less data is available, it raises the exception.

     You can still retrieve the downloaded data in this case, it is stored in the content attribute of the exception instance.

     If no Content-Length header was supplied, urlretrieve() can not check the size of the data it has downloaded, and just returns it. In this case you just have to assume that the download was successful.

     By the way, they're called arguments or parameters, not attributes.

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     4/5

   • What are the benefits and risks of using the StrPtr function in VBA?

     Top Answer

     Answered Sep 21, 2017 · 18 votes

     tldr; There's no real risk to using StrPtr like that, but there's not really a benefit either.

     While it might look like you get a null pointer back from the InputBox call, you actually don't. Compare the result of StrPtr to VarPtr:

     Sub Test() Dim result As String result = InputBox("Enter something.") 'Hit cancel Debug.Print StrPtr(result) '0 Debug.Print VarPtr(result) 'Not 0.End Sub

     That's because InputBox is returning a Variant with a sub-type of VT_BSTR. This code demonstrates (note that I've declared result as a Variant so it doesn't get implicitly cast - more on this below):

     Sub OtherTest() Dim result As Variant result = InputBox("Enter something.") 'Hit cancel Debug.Print StrPtr(result) '0 Debug.Print VarPtr(result) 'Not 0. Debug.Print VarType(result) '8 (VT_BSTR) Debug.Print TypeName(result) 'StringEnd Sub

     The reason why StrPtr returns 0 is because the return value of InputBox is actually malformed (I consider this a bug in the implementation). A BSTR is an automation type that prefixes the actual character array with the length of the string. This avoids one problem that a C-style null terminated string presents automation - you either have to pass the length of the string as a separate parameter or the caller won't know how large to size a buffer to receive it. The problem with the return value of InputBox is that the Variant that it's wrapped in contains a null pointer in the data area. Normally, this would contain the string pointer - the caller would dereference the pointer in the data area, get the size, create a buffer for it, and then read the N bytes following the length header. By passing a null pointer in the data area, InputBox relies on the calling code to check that the data type (VT_BSTR) actually matches what is in the data area (VT_EMPTY or VT_NULL).

     Checking the result as a StrPtr is actually relying on that quirk of the function. When it's called on a Variant, it returns the pointer to the underlying string stored in the data area, and it offsets itself by the length prefix to make it compatible with library functions that require a C-string. That means the StrPtr has to perform a null pointer check on the data area, because it's not returning a pointer to the start of the actual data. Also, like any other VARTYPE that stores a pointer in the data area, it has to dereference twice. The reason VarPtr actually gives you a memory address is that it gives you the raw pointer to whatever variable you pass it (with the exception of arrays, but that's not really in scope here).

     So... it's really no different than using Len. Len just returns the value in the header of the BSTR (no, it doesn't count characters at all), and it also needs a null test for the similar reason that StrPtr does. It makes the logical conclusion that a null pointer has zero length - this is because vbNullstring is a null pointer:

     Debug.Print StrPtr(vbNullString) '<-- 0-

     That said, you're relying on buggy behavior in InputBox. If Microsoft were to fix the implementation (they won't), it would break your code (which is why they won't). But in general, it's a better idea to not rely on dodgy behavior like that. Unless you're looking to treat the user hitting "Cancel" differently than the user not typing anything and hitting "Enter", there really isn't much point in using StrPtr(result) = 0 in favor of the much clearer Len(result) = 0 or result = vbNullString. I'd assert that if you need to make that distinction, you should throw together your own UserForm and explicitly handle cancellation and data validation in your own dialog.

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2. python.land › python-data-types › dictionariesPython Dictionary: How To Create And Use, With Examples

   python.land › python-data-types › dictionaries

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   Jul 14, 2023 · July 14, 2023. The Python dictionary is one of the language’s most powerful data types. In other programming languages and computer science in general, dictionaries are also known as associative arrays. They allow you to associate one or more keys to values. If you are familiar with JSON, you might feel right at home.

3. computersciencewiki.org › index › DictionariesDictionaries - Computer Science Wiki

   computersciencewiki.org › index › Dictionaries

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   Sep 30, 2020 · The main operations on a dictionary are storing a value with some key and extracting the value given the key. It is also possible to delete a key:value pair with del.

4. www.geeksforgeeks.org › python-dictionaryDictionaries in Python - GeeksforGeeks

   www.geeksforgeeks.org › python-dictionary

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   Apr 9, 2024 · Dictionaries in Python is a data structure, used to store values in key:value format. This makes it different from lists, tuples, and arrays as in a dictionary each key has an associated value. Note: As of Python version 3.7, dictionaries are ordered and can not contain duplicate keys. How to Create a Dictionary.

5. www.dataquest.io › blog › python-dictionariesPython Dictionaries: A Comprehensive Tutorial (with 52 Code ...

   www.dataquest.io › blog › python-dictionaries

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   Apr 1, 2022 · A Python dictionary is a data structure that allows us to easily write very efficient code. In many other languages, this data structure is called a hash table because its keys are hashable. We'll understand in a bit what this means. A Python dictionary is a collection of key:value pairs.

6. People also ask

   What is a dictionary in Python?

   • Dictionaries in Python is a data structure, used to store values in key:value format. This makes it different from lists, tuples, and arrays as in a dictionary each key has an associated value. Note: As of Python version 3.7, dictionaries are ordered and can not contain duplicate keys. How to Create a Dictionary

   Dictionaries in Python - GeeksforGeeks

   www.geeksforgeeks.org/python-dictionary/

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   How to use dictionaries in Python?

   • The code begins with a dictionary ‘dict1’ and creates a copy ‘dict2’. It then demonstrates several dictionary operations: clearing ‘dict1’, accessing values, retrieving key-value pairs and keys, removing specific key-value pairs, updating a value, and retrieving values. These operations showcase how to work with dictionaries in Python.

   Dictionaries in Python - GeeksforGeeks

   www.geeksforgeeks.org/python-dictionary/

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   Why should I use a dictionary?

   • If you need to quickly access an element mapped to a specific unique key, choose a dictionary. There is a bit more than that. Dictionaries are much faster if we want to access a specific element because they have a constant runtime, which means that the runtime doesn't depend on the size of the input object.

   Python Dictionaries: A Comprehensive Tutorial (with 52 Code ... - Dataq…

   www.dataquest.io/blog/python-dictionaries/

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   What is a physical dictionary in Python?

   • For example, in a physical dictionary, the definition science that searches for patterns in complex data using computer methods is mapped to the key Data Science. In this Python tutorial, you'll learn how to create a Python dictionary, how to use its methods, and dictionary comprehension, as well as which is better: a dictionary or a list.

   Python Dictionaries: A Comprehensive Tutorial (with 52 Code ... - Dataq…

   www.dataquest.io/blog/python-dictionaries/

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7. en.wikipedia.org › wiki › Glossary_of_computer_scienceGlossary of computer science - Wikipedia

   en.wikipedia.org › wiki › Glossary_of_computer_science

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   This glossary of computer science is a list of definitions of terms and concepts used in computer science, its sub-disciplines, and related fields, including terms relevant to software, data science, and computer programming .

8. towardsdatascience.com › whats-in-a-dictionary-87fWhat’s in a Dictionary?. An overview of a fundamental Python ...

   towardsdatascience.com › whats-in-a-dictionary-87f

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   Jan 18, 2022 · One way to think of a dictionary is as a lookup table made up of pairs of keys and values. It is ideal for storing unordered collections of objects, where the keys and values are associated with each other somehow. Keys are used in order to access their respective values.

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10. www.dictionary.com › browse › computerCOMPUTER Definition & Meaning | Dictionary.com

    www.dictionary.com › browse › computer

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    a person who computes; computist. computer. / kəmˈpjuːtə / noun. a device, usually electronic, that processes data according to a set of instructions. The digital computer stores data in discrete units and performs arithmetical and logical operations at very high speed.