Re: strtok behavior with multiple consecutive delimiters

6 May 2006 18:05:47 -0700
Ian Collins wrote:

If you are going to eliminate output for comparison, you should comment
out the entire last for loop as the C version outputs inline.

Also, to make things more equal, remove the vector, as this is only used
to store tokens for output.

FWIW Below is my version of the comparison. Moving the construction of
the stringstream into the loop really kills performance of the
stringstream version. However this is IMO a more realistic *simple*
useage . I also modified the other code into C++ style but thats by the
way. With this approach the C code is an order of magnitude faster ( I
had to decrease the number of loops to avoid waiting on the
stringstream code), but its not really a fair comparison. The killer of
the C version for me is that you cant have arbitrary length tokens. You
are limited to whatever the value of ABRsize is. If the C coders want
to write a version that can handle arbitrary length C style strings
then it would be a fairer comparison IMO, (though my previous comments
re ease of coding, testing etc remain) BTW I used boost timer for
timing. If you havent got the boost distro you will just have to modify
those parts. I'm too lazy to do that...

Andy Little

#include <sstream>
#include <string>
#include <vector>
#include <iostream>
#include <boost/timer.hpp>

int const ABRsize = 64;
int const NLOOPS = 100000;

const char *
  const char *src,
  char tokchar,
  char *token,
  size_t lgh

int main()
    char tst[] = "this\nis\n\nan\nempty\n\n\nline";

    std::cout << "Timing stringstream version: ";
    boost::timer t0;
    for( int count = 0; count < NLOOPS; ++count) {
        std::stringstream ss;
        ss << tst;
        while (! ss.eof() ){
            std::string str;
    std::cout << t0.elapsed() << "s\n";

    std::cout << "Timing toksplit version: ";
    boost::timer t1;
    for( int count =0;count < NLOOPS;++count){
        char token[ABRsize + 1];
        const char *t = tst;
        while (*t) {
            t = toksplit(t, '\n', token, ABRsize);
    std::cout << t1.elapsed() << "s\n";


const char *toksplit(
                     const char *src, /* Source of tokens */
                      char tokchar, /* token delimiting char */
                      char *token, /* receiver of parsed token */
                      size_t lgh) /* length token can receive */
                                    /* not including final '\0' */
    if (src) {
       while (' ' == *src) *src++;
       while (*src && (tokchar != *src)) {
          if (lgh) {
             *token++ = *src;
       if (*src && (tokchar == *src)) src++;
    *token = '\0';
    return src;
} /* toksplit */

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