std::getline from <string> header is rather slow

• Key: STDCXX-231
• Type: Improvement
• Status: Closed
• Resolution: Fixed
• Priority: Major
• Assignee: Travis Vitek
• Reporter: Martin Sebor
• Component/s: 21. Strings
• Affects Version/s: 4.1.2, 4.1.3, 4.1.4, 4.2.0
• Fix Version/s: 4.2.1

Description

Moved from the Rogue Wave bug tracking database:

****Created By: leroy @ Jan 25, 2001 03:20:01 PM****


Environment
  Compiler : SUNPRO 4.2
  OS : Solaris 2.5.1
  SCL : 1.3.0 (Summer-1999)
  Tools : 7.1.0 (Summer-1999) --> Use only for RWBench

Command line option :
  for debug : 
  CC -xildoff +w +p -g -o Test_dbg.exe test.cc -DRWDEBUG=1 \
-I/opt/RogueWave/Summer-1999/workspaces/SOLARIS251/SUNPRO42/11s \
-I/opt/RogueWave/Summer-1999/workspaces/SOLARIS251/SUNPRO42/11s/include \
-I. -L/opt/RogueWave/Summer-1999/workspaces/SOLARIS251/SUNPRO42/11s/lib -Bstatic -ltls11s -lstd11s -Bdynamic

  for release :
CC -xildoff +w +p -fast -o Test_release.exe test.cc \
-I/opt/RogueWave/Summer-1999/workspaces/SOLARIS251/SUNPRO42/8s \
-I/opt/RogueWave/Summer-1999/workspaces/SOLARIS251/SUNPRO42/8s/include \
-I. -L/opt/RogueWave/Summer-1999/workspaces/SOLARIS251/SUNPRO42/8s/lib -Bstatic -ltls8s -lstd8s -Bdynamic
 (Uploaded file: 997149-test.cc)
                                                                     
**** Entered By: Web @ Thursday, January 25, 2001 2:41:42 AM **** 
Location of uploaded file: 
http://thoth.bco.roguewave.com/uploads/997149-test.cc

View all uploaded files for this incident: 
http://webdev.roguewave.com/admin/tsvw/index.cfm?IncidentID=997149

**** Entered By: Web @ Thursday, January 25, 2001 2:44:56 AM **** 
#web
Please find my test case at the end of the note

Environment
  Compiler : SUNPRO 4.2
  OS : Solaris 2.5.1
  SCL : 1.3.0 (Summer-1999)
  Tools : 7.1.0 (Summer-1999) --> Use only for RWBench

Command line option :
  for debug : 
  CC -xildoff +w +p -g -o Test_dbg.exe test.cc -DRWDEBUG=1 \
-I/opt/RogueWave/Summer-1999/workspaces/SOLARIS251/SUNPRO42/11s \
-I/opt/RogueWave/Summer-1999/workspaces/SOLARIS251/SUNPRO42/11s/include \
-I. -L/opt/RogueWave/Summer-1999/workspaces/SOLARIS251/SUNPRO42/11s/lib -Bstatic -ltls11s -lstd11s -Bdynamic

  for release :
CC -xildoff +w +p -fast -o Test_release.exe test.cc \
-I/opt/RogueWave/Summer-1999/workspaces/SOLARIS251/SUNPRO42/8s 
-I/opt/RogueWave/Summer-1999/workspaces/SOLARIS251/SUNPRO42/8s/include \
-I. -L/opt/RogueWave/Summer-1999/workspaces/SOLARIS251/SUNPRO42/8s/lib -Bstatic -ltls8s -lstd8s -Bdynamic

#Code
#include <string>
#include <fstream.h>
#include <iostream.h>
#include <rw/bench.h>
 
 
class std_string_getline : public RWBench
{
  public:
   std_string_getline() {;}
 
   void doLoop(unsigned long n);
   void idleLoop(unsigned long n);
   void what(ostream& os) const { os << "Standard String Getline : " << endl;}
};
 
class classic_getline : public RWBench
{
  public:
    classic_getline() {;}
 
    void doLoop(unsigned long n);
    void idleLoop(unsigned long n);
    void what(ostream& os) const { os << "Classic Getline : " << endl;}
};
 
int
main(int argc, char** argv)
{
 
  std_string_getline test_std_string;
  test_std_string.parse(argc, argv);
  test_std_string.go();
  test_std_string.report(cout);
 
  classic_getline test_classic_getline;
  test_classic_getline.parse(argc, argv);
  test_classic_getline.go();
  test_classic_getline.report(cout);
}
 
void
std_string_getline::doLoop(unsigned long n)
{
  while (n--)
  {
    ifstream toRead(__FILE__);
    string line;
    line.reserve(512);
 
    while (!(toRead.eof()))
    {
      getline(toRead, line, '\n');
    }
  }
}
 
void
std_string_getline::idleLoop(unsigned long n)
{
  while (n--)
  {
    ifstream toRead(__FILE__);
    string line;
    line.reserve(512);
  }
}
 
void
classic_getline::doLoop(unsigned long n)
{
  while (n--)
  {
    ifstream toRead(__FILE__);
    char cLine[512];
    string line;
    line.reserve(512);
 
    while (!(toRead.eof()))
    {
      toRead.getline(cLine, 512);
      line = cLine;
    }
  }
}
 
void
classic_getline::idleLoop(unsigned long n)
{
  while (n--)
  {
    ifstream toRead(__FILE__);
    char cLine[512];
    string line;
    line.reserve(512);
  }
}

#EndCode                

There appears to be something to this.  I ran the program and here is the output:

Sun C++ 

Standard String Getline : 

Iterations:                 1
Inner loop operations:      1000
Total operations:           1000
Elapsed (user) time:        18.18
Operations per second:      55.0055

Sun C++ 

Classic Getline : 

Iterations:                 5
Inner loop operations:      1000
Total operations:           5000
Elapsed (user) time:        4.67
Kilo-operations per second: 1.07066