How to add a newline after a certain number of characters

function [strMultiLines] = nCharLine(strtxt, n)
Length=length(strtxt);
strMultiLines=strtxt;
strMultiLines=[strMultiLines(1:n) char(10) strMultiLines(n+1:length(strMultiLines))];    
end

This is my code, and It gives me this kind of output when run

'Hi th
 ere, Im Jack'

What I want, is for the code to keep splitting after a certain number of characters. How can I do this? I have tried using a while loop, yet it didn't work for me.

Answer 1

[dpb]

function strMultiLines=nCharLine(strtxt, n)
  fmt=[repmat('%c',1,n) '\n'];
  strMultiLines=sprintf(fmt,strtxt);
end

for input char() array. If cellstr, must dereference it for sprintf

Answer 2

[Walter Roberson]

while number of remaining characters > n
    remove and record the first n characters
    add them and newline to output
end
add remaining characters to output

However suppose that you set n to (say) 4, and there is an exact multiple of 4 characters in the input:

'ABCDEFGH'

then clearly you should split after the first group of 4,

'ABCD|EFGH'

but should you also split at the end of the group?

'ABCD|EFGH|'

? Doing so would follow the rule about adding a newline after a certain number of characters... but is that really the rule you want? Is perhaps the real rule about splitting splitting the string every N characters? Because "splitting" implies that you do not put on a trailing newline if it would be at the end.

[John Jamieson]

This is the rule: There is a newline code sequence in place of the last space before or at the n th position of each line

[dpb]

That's what the Answer below does, precisely.

[John Jamieson]

Sadly, nother rule is that I cant use repmat or sprintf. I can mainly only use basic built in string manipulation functions like strfind, size and length.

[dpb]

You didn't tell us this was homework...it's frustrating that instructors use such artifices as crutches in their teaching. Creates wrong impression of how MATLAB should be used that many never get over, I'm afraid.

Walter gave you the pseudo code...have you tried to implement it?

[Walter Roberson]

'Hi th
 ere, Im Jack'

With the rule you describe, the newline would go between the Hi and the there, and it becomes unclear what to do if there is a long word.

[John Jamieson]

My new code goes something like this:

function [strMultiLines] = nCharLine(strtxt, n)
Length=length(strtxt);
strMultiLines=strtxt;
    while Length>n
     x=[strMultiLines(1:n(1)) char(10) strMultiLines(n(1)+1:Length)]; 
     strMultiLines=x;
     Length=length(strMultiLines);
    end
end

The only problem is that it adds to length after going through the while loop, when I want it to read the longest row. for examle if I have

Hi th

ere, Im Jack

I want it to read the characters in the second row, not the first since it's already been seperated.

[Walter Roberson]

"This is the rule: There is a newline code sequence in place of the last space before or at the n th position of each line"

That rule never splits in the middle of a word. It splits at spaces, changing the space to newline.

The rule is not clear on several respects. I suspect that the desired outcome is

Hi
there,
Im
Jack

but a more consistent interpretation would be

Hi
there, Im
Jack

[John Jamieson]

The only problem I have with this new explanation of the rule, as simple as it is, is that I can now disregard the n parameter altogether. Which does not seem correct to me.

The full rule for this function is as follows

Create a function called nCharLine that receives a string and an integer as parameters and divides the string into lines of max length indicated by the integer:

(1) Parameters: strText – a string of characters to divide into lines,

n – an integer indicating the max length of lines;

Return value: strMultiLines, that contains the same string as the parameter except:

(a) There is a newline code sequence in place of the last space before or at the n th position of each line,

(b) A newline code sequence is defined as ASCII-13 followed by ASCII-10, Note that there is NO newline code sequence at the end of the file.

[John Jamieson]

I can see how I may have misinterpreted this now

[John Jamieson]

Never mind I think I got it, thank you for your help. Your advice really helped me

[Walter Roberson]

Suppose n were 7, then the desired output would be

Hi
there,
Im Jack

and if n were 9 then the desired output would be

Hi there,
Im Jack

and for 12 it would be

Hi there, Im
Jack

That is goes roughly:

if there are less than n characters left,
    emit the remaining characters
else
    look forward n characters
    starting there,
   if the current character is space
     emit the buffer up to but excluding the current character
     emit end of line
     remove from the beginning of the buffer up to the current character
     stop checking here
   else
       move backwards and check again
   end
end

This does not tell you what to do if you are positioned to a word longer than n. Historically, there are several different solutions that have been used:

• break the line right where you are, after the n'th character
• keep looking forward and break at the first whitespace
• insert a dash before the current character and put in a break -- supe-\ncali-\nfrag-\nilis-\n
• analyze the current word to determine where its syllables are, and break at the syllable boundary before the current character
• analyze the current word to determine where its syllables are, and break at the preferred syllable boundary if it is within a certain number of characters before the current character, and otherwise break at the syllable boundary closest to the current character

The versions that examine syllables can be a lot more work to implement. Especially in English, as there are words whose syllable breaks depend upon context, like unionized which can be un-ion-ized (pertaining to labour unions) or un-i-on-ized (pertaining to chemical ions)