CODEWITHSUNDEEP
postscript
Mark Harrison
Mark Harrison

Reputation: 304654

Postscript: concatenate two strings?

How do I concatenate two strings in Postscript?

(foo) (bar) ??? -> (foobar)

Upvotes: 7

Views: 4267

Answers (3)

lhf
lhf

Reputation: 72402

PostScript doesn't have a built-in string concatenation operator. You need to write some code for that. For instance

 /concatstrings % (a) (b) -> (ab)  
   { exch dup length    
     2 index length add string    
     dup dup 4 2 roll copy length
     4 -1 roll putinterval
   } bind def

(code from https://en.wikibooks.org/wiki/PostScript_FAQ/Programming_PostScript#How_to_concatenate_strings%3F.)

Upvotes: 10

luser droog
luser droog

Reputation: 19504

Same idea generalized to any number of strings. Earlier revisions use a helper function acat which takes an array of strings (for easy counting and iteration). This version uses fancier loops and stack manipulation to avoid allocating an array. This version would also concatenate arrays by changing the string operator to array.

% (s1) (s2) (s3) ... (sN) n  ncat  (s1s2s3...sN)
/ncat {        % s1 s2 s3 .. sN n                   % first sum the lengths
    dup 1 add  % s1 s2 s3 .. sN n n+1 
    copy       % s1 s2 s3 .. sN n  s1 s2 s3 .. sN n
    0 exch     % s1 s2 s3 .. sN n  s1 s2 s3 .. sN 0 n 
    {   
        exch length add 
    } repeat             % s1 s2 s3 .. sN  n   len  % then allocate string
    string exch          % s1 s2 s3 .. sN str   n   
    0 exch               % s1 s2 s3 .. sN str  off  n
    -1 1 {               % s1 s2 s3 .. sN str  off  n  % copy each string
        2 add -1 roll       % s2 s3 .. sN str  off s1  % bottom to top
        3 copy putinterval  % s2 s3 .. sN str' off s1
        length add          % s2 s3 .. sN str' off+len(s1)
                            % s2 s3 .. sN str' off'
    } for                               % str' off'
    pop  % str'
} def 

(abc) (def) (ghi) (jkl) 4 ncat == %(abcdefghijkl)

Upvotes: 8

jdaw1
jdaw1

Reputation: 251

There are useful subroutines in

http://www.jdawiseman.com/papers/placemat/placemat.ps

including Concatenate (accepting two strings) and ConcatenateToMark (mark string0 string1 …).

Upvotes: 3

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