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Conference turris::c_plus_plus

Title:C++
Notice:Read 1.* and use keywords (e.g. SHOW KEY/FULL KIT_CXX_VAX_VMS)
Moderator:DECCXX::AMARTIN
Created:Fri Nov 06 1987
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:3604
Total number of notes:18242

3592.0. "+= copying strings??" by KERNEL::PULLEY (Come! while living waters flow) Thu May 29 1997 10:18

    Hi,
    
    On Digital UNIX v4.0b, C++ v5.5-004, I've tryed the program below which
    takes a few minutes to run.
    It basically gets slower & slower.
    Does my system/process just need tuning?
    
    Thanks,
    Steve.
    
    #include <string>
    
    void main ()
    {
        string dots (10000, '.');
        string s;
            for (int i = 0; i < 10; i++)
              {
                s+=dots;
                cerr << "  " << i << ": size = " << s.size() << endl;
              }
    
    }
T.RTitleUserPersonal
Name		DateLines
3592.1V5.5 string has performance problems, can you upgrade to V5.6?DECC::J_WARDThu May 29 1997 10:3136
I'd suggest upgrading to V5.6, this is the Rogue Wave
implementation and it also has copy-on-write.

for V5.5:

cosf.zko.dec.com> time a.out
  0: size = 10000
  1: size = 20000
  2: size = 30000
  3: size = 40000
  4: size = 50000
  5: size = 60000
  6: size = 70000
  7: size = 80000
  8: size = 90000
  9: size = 100000
68.42u 0.01s 1:08 99% 0+3k 0+0io 0pf+0w

for V5.6:

cosf.zko.dec.com> time a.out
  0: size = 10000
  1: size = 20000
  2: size = 30000
  3: size = 40000
  4: size = 50000
  5: size = 60000
  6: size = 70000
  7: size = 80000
  8: size = 90000
  9: size = 100000
0.01u 0.01s 0:00 100% 0+2k 0+0io 0pf+0w