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Questions tagged [string-concatenation]

String concatenation is the operation of joining two character strings end-to-end.

In particular in the theory of computation, the concatenation operation on strings is generalized to an operation on sets of strings as follows:

For two sets of strings S1 and S2, the concatenation S1S2 consists of all strings of the form vw where v is a string from S1 and w is a string from S2. In this definition, the string vw is the ordinary concatenation of strings v and w as defined in the introductory section. In this context, sets of strings are often referred to as formal languages.

Programming languages often provide operators (such as the + sign) to simplify concatenation of strings. For example, "s1" + "s2" would result in "s1s2".

2012 questions
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pyspark generate row hash of specific columns and add it as a new column

I am working with spark 2.2.0 and pyspark2. I have created a DataFrame df and now trying to add a new column "rowhash" that is the sha2 hash of specific columns in the DataFrame. For example, say that df has the columns: (column1, column2, ...,…
msashish
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Concatenate inputs in string while in loop

I have a variable of sources that is basically a string of comma-separated elements: SOURCES="a b c d e" I want the user to input one destination for each of this source, and I want hence to store this input into a string looking like the above but…
Matteo NNZ
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Concatenation of LPWSTR strings

In Visual C++, I have a LPWSTR mystring; which is already defined somewhere else in the code. I want to create a new LPWSTR containing: "hello " + mystring + " blablabla" (i.e. a concatenation) I'm getting mad with such a simple thing…
Basj
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Performance: Java's String.format

Possible Duplicate: Should I use Java's String.format() if performance is important? I was wondering if is good to use String.format in Java apps instead of StringBuilder... so, I just write a simple test, like this: public static void…
caarlos0
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T-SQL: issue with string concat

I have a set of audio files with names GreenLine1.mp3, GreenLine2.mp3 e.t.c. I'm going to write them into a table as BLOB (I use MS SQL Server'08), here's my sql request: DECLARE @aud AS VARBINARY(MAX) DECLARE @num AS INT -- Load the audio…
Ilya Blokh
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lisp function to concatenate a list of strings

I need to write a function that will concatenate a list into a string. example: (concatString (quote ("hello" " world"))) ==> "hello world" here is what i have so far: (defun concatString (list) "A non-recursive function that concatenates a…
MBU
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C# FormattableString concatenation for multiline interpolation

In C#7, I'm trying to use a multiline interpolated string for use with FormttableString.Invariant but string concatenation appears to be invalid for FormttableString. Per the documentation: A FormattableString instance may result from an…
Eugene
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Is += more efficient than concat?

I've been reading code produced by other developers on my team, they seem to favor using += for String concatenation, whereas I prefer using .concat() as it feels easier to read. I'm trying to prepare an argument as to why using .concat() is better,…
Jimmy
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Concatenate two char arrays?

If I have two char arrays like so: char one[200]; char two[200]; And I then want to make a third which concatenates these how could I do it? I have tried: char three[400]; strcpy(three, one); strcat(three, two); But this doesn't seem to work. It…
ingh.am
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C# Compile-Time Concatenation For String Constants

Does C# do any compile-time optimization for constant string concatenation? If so, how must my code by written to take advantage of this? Example: How do these compare at run time? Console.WriteLine("ABC" + "DEF"); const string s1 =…
Joseph Sturtevant
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nvarchar concatenation / index / nvarchar(max) inexplicable behavior

I today ran into a really weird problem in SQL Server (both 2008R2 and 2012). I'm trying to build up a string using concatenation in combination with a select statement. I have found workarounds, but I would really like to understand what's going on…
bartlaarhoven
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String concatenation with ASP.NET MVC3 Razor

i'm trying to concatenate a string in asp.net mvc 3 razor and i'm getting a little sintax problem with my cshtml. i what to generate an id for my checkboxes on a foreach statement, and my checkboxes should start with "chk" and what to cancatenate a…
Flavio CF Oliveira
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How to split string preserving whole words?

I need to split long sentence into parts preserving whole words. Each part should have given maximum number of characters (including space, dots etc.). For example: int partLenght = 35; string sentence = "Silver badges are awarded for longer term…
jlp
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Is it possible to concatenate heredoc string in PHP..?

With normal PHP string you can do this: $str = "Hello "; $str .= "world"; $str .= "bla bla bla"; $str .= "bla bla bla..."; But can you do the same with heredoc string..? $str = <<
pnichols
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C#: most readable string concatenation. best practice

Possible Duplicate: How should I concatenate strings? There are several ways to concat strings in everyday tasks when performance is not important. result = a + ":" + b result = string.Concat(a, ":", c) result = string.Format("{0}:{1}", a,…
Andrew Florko
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