why is a blank ignored in strcat

6 次查看(过去 30 天)
as an example, the following code:
strcat(num2str(1,'%02.0f'), '-', num2str(2), ' ', num2str(3), ':', num2str(4,'% 2.0f'))
produces:
01-23:4
whereas I want:
01-2 3: 4
Seems pretty simple but ... would someone help please?

采纳的回答

Jan
Jan 2013-10-15
编辑:Jan 2013-10-15
'% 2.0f' adds a leading space on demand only, so you want: ' %2.0f'.
But this would be nicer, faster and less confusing:
sprintf('%02.0f-%d %d: % 2.0f', 1, 2, 3, 4)
To get around this ugly space gimmicks, which come from the backward compatibility to times before cell strings have been invented, I'm using a dedicated function to join strings: FEX: CStrCatStr. But this is designed for cell strings and for strings horzcat works sufficiently without deleting spaces smartly.

更多回答(2 个)

Friedrich
Friedrich 2013-10-15
Hi,
the doc states:
"For character array inputs, strcat removes trailing ASCII white-space characters: space, tab, vertical tab, newline, carriage return, and form-feed. For cell array inputs, strcat does not remove trailing white space."
So you can use:
strcat({num2str(1,'%02.0f')}, {'-'},{num2str(2)}, {' '}, {num2str(3)}, {':'}, {num2str(4,'% 2.0f')})
or dont use strcat and use []:
[num2str(1,'%02.0f'), '-', num2str(2), ' ', num2str(3), ':', num2str(4,'% 2.0f')]
  4 个评论
Image Analyst
Image Analyst 2013-10-15
I was talking to Ross. I know Frederich knows both methods and I agree with you about why Frederich answered that way. I was trying to point Ross towards the method that I find gives me much more control with much less complicated syntax.
Jan
Jan 2013-10-15
@Image Analyst: I've inserted "@Ross" in your comment and have removed by concerning question.

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Jos (10584)
Jos (10584) 2013-10-15
编辑:Jos (10584) 2013-10-15
This used to be my workaround for the way strcat handles spaces:
strrep(strcat('AAA', '#SPACE#', 'BBB'),'#SPACE#',' ')
  2 个评论
Jan
Jan 2013-10-15
What about: ['AAA', ' ', 'BBB'] ?
Jos (10584)
Jos (10584) 2013-10-15

I should have stressed the word used ...

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