How to convert string to string object

How to convert string to string object

How to Convert a Unicode String to a String Object in Python?

This tutorial will show you how to convert a Unicode string to a string in Python. If you already know about Unicode, you can skip the following background section and dive into the problem right away.

Table of Contents

Background Unicode

A bit about Unicode from Wikipedia.

Unicode is a character encoding standard that includes characters from almost all written languages ​​in the world. The standard is now prevalent on the Internet.

The standard was proposed in 1991 by the non-profit organization “Unicode Consortium” (Unicode Inc). The use of this standard makes it possible to encode a very large number of characters from different writing systems: in documents encoded according to the Unicode standard, Chinese hieroglyph, mathematical symbols, letters of the Greek alphabet, Latin and Cyrillic alphabet, symbols of musical notation become unnecessary, and switching code pages becomes unnecessary.

In Unicode, there are several forms of representation (Unicode transformation format, UTF): UTF-8, UTF-16 (UTF-16BE, UTF-16LE) and UTF-32 (UTF-32BE, UTF-32LE). In the data stream, UTF-16 the low byte can be written either before the high order (UTF-16 little-endian, UTF-16LE) or after the high order (UTF-16 big-endian, UTF-16BE). Likewise, there are two variants of the four-byte form of presentation – UTF-32LE and UTF-32BE. All of them are also called encodings.

Microsoft Windows NT and systems based on it mainly use the UTF-16LE form. UNIX-like operating systems GNU / Linux, BSD, and Mac OS X adopt UTF-8 for files and UTF-32 or UTF-8 for in-memory character handling.

Often we receive as input a string of Unicode characters, which is not readable by a regular user, but has many advantages over regular text, for example, it takes up less memory space or takes less time to process and further transfer. Depending on the further requirements for the Unicode string or depending on the environment (whether it be an operating system or software), it is necessary to determine the encoding that can and should be used.

UTF-8 is now the dominant encoding on the web. UTF-8, in comparison with UTF-16, gives the greatest gain in compactness for texts in Latin, since Latin letters, numbers, and the most common punctuation marks are encoded in UTF-8 by only one byte, and the codes of these characters correspond to their codes in ASCII.

UTF-16 is an encoding that allows writing Unicode characters in the ranges U + 0000 … U + D7FF and U + E000 … U + 10FFFF (with a total of 1112064). Moreover, each character is written in one or two words (surrogate pair).

UTF-32 is a way of representing Unicode in which each character is exactly 4 bytes. The main advantage of UTF-32 over variable-length encodings is that Unicode characters in it are directly indexable, so finding a character by its position number in the file can be extremely fast, and getting any character in the n-th position is an operation that always takes the same time. It also makes it very easy to replace characters in UTF-32 strings. In contrast, variable-length encodings require sequential access to the n-th character, which can be very time-consuming. The main disadvantage of UTF-32 is its inefficient use of space since four bytes are used to store any character.

Problem Formulation

Suppose we have a Unicode string and we need to convert it to a Python string.

Let’s make sure of the input data type:

Method 1. String

In Python 3, all text is Unicode strings by default, which also means that u’

‘ syntax is no longer used.

Most Python interpreters support Unicode and when the print function is called, the interpreter converts the input sequence from Unicode-escape characters to a string.

It makes no sense to check the data type after applying the string method.

Method 2. Repr()

The built-in repr() function returns a string containing the printable formal representation of an object.

Check the data type:

Method 3. Module Unicodedata, function normalize

The normalize() function of the Unicodedata module returns the normal form for a Unicode string. Valid values ​​for the form are NFC, NFKC, NFD, and NFKD.

The Unicode standard defines various forms of Unicode string normalization based on the definition of canonical equivalence and compatibility equivalence. In Unicode, multiple characters can be expressed in different ways. For example, the character U + 00C7 (LATIN CAPITAL LETTER C WITH CEDILLA) can also be expressed as the sequence U + 0043 (LATIN CAPITAL LETTER C) U + 0327 (COMBINING CEDILLA).

There are two normal forms for each character: normal form C and normal form D. Normal form D (NFD) is also known as canonical decomposition and translates each character into decomposed form. Normal Form C (NFC) first applies canonical decomposition, then re-creates the pre-combined characters.

In addition to these two forms, there are two additional normal forms based on the equivalence of compatibility. Some characters which are supported in Unicode, are usually combined with other characters. For example, U + 2160 (ROMAN NUMERAL ONE) is indeed the same as U + 0049 (LATIN CAPITAL LETTER I). However, it is supported in Unicode for compatibility with existing character sets such as gb2312.

The normal form KD (NFKD) will apply compatibility decomposition, that is, replace all compatibility symbols with their equivalents. The normal form KC (NFKC) applies compatibility decomposition first and then canonical composition.

Even though two Unicode strings are normalized and look the same to humans if one has combined characters and the other does not, they may not match.

Let’s check the data type after normalization:

Method 4. List Comprehension and str.join

The str.join() method returns a string that is the concatenation (union) of all the elements of the strings of the iterable.

In the final line, the elements are combined with each other using the str separator string.

If there are any non-string values in the iterable sequence, including bytes, then raised the TypeError exception.

Let’s check how it works:

» – an empty string character joins the elements of the list that we have compiled from the elements of string A using the join method.

Since we have indicated to wrap each iterable of the list with the str function, we can safely assume that the result will be the desired data type:

Method 5. Library ftfy

The full name of this library is Fixes text for you. It is designed to turn bad Unicode strings (“quotesâ€\x9d or ü) into good Unicode strings (“quotes” or ü respectively).

Let’s see how it works in our example:

What does it do with the output data type:

Great, that’s what you need, the main thing is that the library remains accessible;)

Method 6. Module io

The IO module is applicable when you need to perform an I / O operation on files (for example, reading or writing files). You can use the built-in read() and write() methods to read or write a file, but this module gives us much more code options for these operations, such as writing or reading from a buffer.

In our simple example, it would look like this:

io.StringIO works with data of the string type, both in input and output. Whenever an input string or data stream consists of bytes or Unicode characters, the encoding or decoding of the data is performed transparently, and optional translation of environment-specific newlines is taken into account.

Method 7. Format

This method seems to be the most powerful and effective since it allows you to work with all data types: bytes, strings, int, and float numbers in different representations (octal, decimal, hexadecimal in different registers) using the mini-language specification, which allows you to specify not only the data type, but also offset, rounding, filling with characters to the required length, and also allows you to work with dictionaries and their indices in various variations.

Let’s check with our example:

Here ‘s’ is the type of the formatted object – string, used by default. More details about the specification and syntax here.

Related Tutorials

Why Finxter?

Learning Resources

How to: Convert between various string types

This article shows how to convert various Visual C++ string types into other strings.

In all cases, a copy of the string is made when converted to the new type. Any changes made to the new string won’t affect the original string, and vice versa.

For more background information about converting narrow and wide strings, see Converting between narrow strings and wide strings.

Run the examples

To run the examples in Visual Studio 2022, you can either create a new C++ Windows Console App or, if you have installed C++/CLI support, you can create a CLR Console App (.NET Framework).

If you create a CLR Console App, you don’t have to make the following changes to the compiler and debugger settings. However, you’ll need to add #include «pch.h» to the top of each example.

Either way, add comsuppw.lib to Project Properties > Linker > Input > Additional Dependencies.

If you create a new C++ Windows Console app to run the examples, make the following project changes:

The /clr switch conflicts with some compiler switches that are set when you create a C++ Windows Console App project. The following links provide instructions for where in the IDE you can turn off the conflicting switches:

Example: Convert from char *

Description

This example demonstrates how to convert from a char * to the string types listed above. A char * string (also known as a C-style string) uses a terminating null to indicate the end of the string. C-style strings usually require 1 byte per character, but can also use 2 bytes. In the examples below, char * strings are sometimes referred to as multibyte character strings because of the string data that results from converting from wide Unicode strings. Single byte and multibyte character ( MBCS ) functions can operate on char * strings.

For information about running and debugging this example, see Run the examples.

Example: Convert from wchar_t *

Description

For information about running and debugging this example, see Run the examples.

Example: Convert from _bstr_t

Description

This example demonstrates how to convert from a _bstr_t to other string types. The _bstr_t object encapsulates wide character BSTR strings. A BSTR string has a length value and doesn’t use a null character to terminate the string, but the string type you convert to may require a terminating null character.

For information about running and debugging this example, see Run the examples.

Example: Convert from CComBSTR

Description

For information about running and debugging this example, see Run the examples.

Example: Convert from CString

Description

This example demonstrates how to convert from a CString to other string types. CString is based on the TCHAR data type, which in turn depends on whether the symbol _UNICODE is defined. If _UNICODE isn’t defined, TCHAR is defined to be char and CString contains a multibyte character string; if _UNICODE is defined, TCHAR is defined to be wchar_t and CString contains a wide character string.

CStringA contains the char type and supports single-byte or multibyte strings. CStringW is the wide character version. CStringA and CStringW don’t use _UNICODE to determine how they should compile. CStringA and CStringW are used in this example to clarify minor differences in buffer size allocation and output handling.

For information about running and debugging this example, see Run the examples.

Example: Convert from basic_string

Description

This example demonstrates how to convert from a basic_string to other string types.

For information about running and debugging this example, see Run the examples.

Example: Convert from System::String

Description

This example demonstrates how to convert from a wide character System::String to other string types.

For information about running and debugging this example, see Run the examples.

Converting between narrow and wide strings

Legacy C and Windows apps use code pages rather than Unicode encodings when handling narrow strings and wide strings.

On an en-US language version of Windows, the code page defaults to 1033. If you install a different language of Windows, it will have a different code page. You can change it using the control panel.

Python Object to String

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Definition of Python Object to String

Python object in python refers to the object which is used by the other functions in order to get the direct conversion of one data type present within the object into another data type present in the other object. Python is all about objects thus the objects can be directly converted into strings using methods like str() and repr(). Str() method is used for the conversion of all built-in objects into strings. Similarly, repr() method as part of object conversion method is also used to convert an object back to a string.

Syntax:

Web development, programming languages, Software testing & others

Initialize an object first :

Need to perform Typecasting in order to get the object for converting into a string.

Need to print the object for getting the details about the data type present within the object.

Need to make the final casting into object_strng for getting the final value of string.

How to Convert Object to String in Python?

There are ways to convert object into string in Python with some of the rules and regulations. The working flow includes many of the constraints as mentioned:

Examples

Let us discuss examples of Python Object to String.

Example #1

This program demonstrates the conversion of a variable being assigned with an integer directly into the string type object as shown. With an error which says that if in case the variable assigned includes text will result in a type error.

Out-String

Outputs input objects as a string.

Syntax

Description

The Out-String cmdlet converts input objects into strings. By default, Out-String accumulates the strings and returns them as a single string, but you can use the Stream parameter to direct Out-String to return one line at a time or create an array of strings. This cmdlet lets you search and manipulate string output as you would in traditional shells when object manipulation is less convenient.

Examples

Example 1: Get the current culture and convert the data to strings

This example gets the regional settings for the current user and converts the object data to strings.

To view the Out-String array, store the output to a variable and use an array index to view the elements. For more information about the array index, see about_Arrays.

Example 2: Working with objects

Get-Alias gets the System.Management.Automation.AliasInfo objects, one for each alias, and sends the objects down the pipeline. Out-String uses the Stream parameter to convert each object to a string rather than concatenating all the objects into a single string. The System.String objects are sent down the pipeline and Select-String uses the Pattern parameter to find matches for the text gcm.

If you omit the Stream parameter, the command displays all the aliases because Select-String finds the text gcm in the single string that Out-String returns.

Example 3: Use the Width parameter to prevent truncation.

Parameters

Specifies the objects to be written to a string. Enter a variable that contains the objects, or type a command or expression that gets the objects.

Type:PSObject
Position:Named
Default value:None
Accept pipeline input:True
Accept wildcard characters:False

Removes all newlines from output generated by the PowerShell formatter. Newlines that are part of the string objects are preserved.

This parameter was introduced in PowerShell 6.0.

Type:SwitchParameter
Position:Named
Default value:False
Accept pipeline input:False
Accept wildcard characters:False

By default, Out-String outputs a single string formatted as you would see it in the console including any blank headers or trailing newlines. The Stream parameter enables Out-String to output each line one by one. The only exception to this are multiline strings. In that case, Out-String will still output the string as a single, multiline string.

Type:SwitchParameter
Position:Named
Default value:False
Accept pipeline input:False
Accept wildcard characters:False

Specifies the number of characters in each line of output. Any additional characters are wrapped to the next line or truncated depending on the formatter cmdlet used. The Width parameter applies only to objects that are being formatted. If you omit this parameter, the width is determined by the characteristics of the host program. In terminal (console) windows, the current window width is used as the default value. PowerShell console windows default to a width of 80 characters on installation.

Type:Int32
Position:Named
Default value:None
Accept pipeline input:False
Accept wildcard characters:False

Inputs

Outputs

Out-String returns the string that it creates from the input object.

Notes

The cmdlets that contain the Out verb don’t format objects. The Out cmdlets send objects to the formatter for the specified display destination.

Источники информации:

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