strcat including space (i.e, ' ')

I have to concatenate words, including spaces
Ex. a='word1'; b='word2';c=strcat(a,' ',b);
I need 'word1 word2', however, the value on c is 'word1word2'
Can you help me?

 Réponse acceptée

Walter Roberson
Walter Roberson le 11 Juin 2011
Modifié(e) : MathWorks Support Team le 8 Nov 2018

28 votes

To include spaces when concatenating character vectors, use square brackets.
a = 'word1';
b = 'word2';
c = [a ' ' b]
The “ strcat ” function ignores trailing whitespace characters in character vectors. However, “strcat” preserves them in cell arrays of character vectors or string arrays.
a = {'word1'};
b = {'word2'};
c = strcat(a,{' '},b)
You also can use the “plus” operator to combine strings. Starting in R2017a, use double quotes to create strings. For more information on strings, see the “ string ” data type.
a = "word1";
b = "word2";
c = a + " " + b

6 commentaires

Paulo Silva
Paulo Silva le 11 Juin 2011
Walter I'm sorry but this time I have to disagree with your answer, you said strcat({'word1'},{' '},{'word2'}) but that doesn't work properly for the question and example, that's working with cells (input and output) and the user just wants strings.
Walter Roberson
Walter Roberson le 11 Juin 2011
So? The user also wanted variables instead of constants. I illustrated the principle and the user can adapt from there, such as using
c = char(strcat(a,{' '},b));
Jan
Jan le 11 Juin 2011
@CELL/STRCAT is a not efficiently implemented M-function. It is easy to improve it and remove the strange deleting of marinal spaces. This behaviour is kept from the Matlab 4 times, before CELL-strings allowed to create a container for strings of different lengths.
Paulo Silva
Paulo Silva le 12 Juin 2011
variables, constants, strings and cells
Too many assumptions for such small question but it's all ok
Captain Karnage
Captain Karnage le 26 Août 2022
Modifié(e) : Voss le 26 Août 2022
FYI for anyone else reading, I had a cell array of strings and I wanted to concatenate the same string (with a space in it) to each of the strings in the cell array (no spaces in these strings). The square bracket (first) method of course doesn't work, neither does the "plus" operator (third/last) method for that. However, the "strcat" using a single cell array with a space (2nd/middle above) method does work.
To specifically show an example:
a = 'Addme';
b = { 'to', 'each', 'one', 'of', 'these', 'words', 'with', 'a', 'space'};
c = strcat(a,{' '},b)
c = 1×9 cell array
{'Addme to'} {'Addme each'} {'Addme one'} {'Addme of'} {'Addme these'} {'Addme words'} {'Addme with'} {'Addme a'} {'Addme space'}
Walter Roberson
Walter Roberson le 26 Août 2022
Modifié(e) : Walter Roberson le 26 Août 2022
a = 'Addme';
b = { 'to', 'each', 'one', 'of', 'these', 'words', 'with', 'a', 'space'};
strjoin([a, b])
ans = 'Addme to each one of these words with a space'
a + " " + b
ans = 1×9 string array
"Addme to" "Addme each" "Addme one" "Addme of" "Addme these" "Addme words" "Addme with" "Addme a" "Addme space"

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Plus de réponses (4)

Paulo Silva
Paulo Silva le 11 Juin 2011

5 votes

c=[a ' ' b]
strcat ignores trailing ASCII white space characters and omits all such characters from the output. White space characters in ASCII are space, newline, carriage return, tab, vertical tab, or form-feed characters, all of which return a true response from the MATLAB isspace function. Use the concatenation syntax [s1 s2 s3 ...] to preserve trailing spaces. strcat does not ignore inputs that are cell arrays of strings.

2 commentaires

Daniel Foose
Daniel Foose le 23 Fév 2018
This is better than the accepted answer because it keeps the type the same. The accepted answer returns a cell with a string in it (which is different from a string). This answer returns a string.
The accepted answer returns a cell with a character vector in it. Strings did not exist in R2011a. If strings were being used then you would use a different approach:
>> a = "word1"; b = "word2"; a + " " + b
ans =
"word1 word2"
This requires R2017a or later. For R2016b,
>> a = string('word1'); b = string('word2'); a + ' ' + b
and before R2016b strings did not exist.

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Jy·Li
Jy·Li le 25 Mai 2023

3 votes

c=strcat(a,32,b); % the unicode value of ' ' is 32
Usman Nawaz
Usman Nawaz le 6 Sep 2020

2 votes

use double quotes instead of single quotes, worked for me.

1 commentaire

Walter Roberson
Walter Roberson le 6 Sep 2020
That can be useful, but the output would be a string() object instead of a character vector. string() objects can be useful, but they need slightly different handling than character vectors.
string() objects became available in R2016b; using double-quotes to indicate string objects became available in R2017a.

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R P
R P le 11 Juin 2011

0 votes

Thank you, Walter

3 commentaires

Paulo Silva
Paulo Silva le 11 Juin 2011
Please always test the answers provided before accepting them, Walter answer isn't correct (this time).
Walter Roberson
Walter Roberson le 11 Juin 2011
>> strcat({'word1'},{' '},{'word2'})
ans =
'word1 word2'
You can dereference this or cell2mat it if you want the string itself as output.
Jan
Jan le 11 Juin 2011
@Walter: CELL2MAT is not efficient here. S{1} is nicer.

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