3 ms·

> Being able to concatenate strings by simply saying "a + b" is a great productivity boost (coming from C++) C++ has had this operator overloaded for strings f

> Being able to concatenate strings by simply saying "a + b" is a great productivity boost (coming from C++) C++ has had this operator overloaded for strings for decades. With regard to the size of compiled executables, I can't really say much except "that's not what it's made for". If you need to ship compiled executables to people, Python is an extraordinarily inappropriate choice; stick with C++.

dkersten 12y ago
I've often heard it said that if you're not using std::string for strings in C++, you're (arguably) not using C++
- GnarfGnarf 12y ago
  I just did a test using std:: and old-fashioned char[]. The fancy std:: is fifteen times slower than the strcat(). In a loop with intensive string manipulation, this could cause the program to get back to you in 15 seconds instead of 1 second. You don't mind waiting? Here's the code (Visual Studio 2010): #include <string> #include <time.h> char buf[64], buf2[64]; clock_t start = clock(); for(i = 0; i < 100000; i++) { _snprintf(buf, sizeof(buf), "%d", i); _snprintf(buf2, sizeof(buf2), "%d", i * i); #if defined FAST strcat(buf, buf2); #else std::string s1 = buf; std::string s2 = buf2; std::string s3 = s1 + s2; #endif } _snprintf(buf, sizeof(buf), "%.4f\n", (float)(clock() - start) / (float)CLK_TCK); OutputDebugString(buf);
  - theseoafs 12y ago
    You should be using `+=` to build strings incrementally in C++, not using `+` repeatedly.
  - 30thElement 12y ago
    Well of course you're getting a speed difference, look at how much extra work you're doing in the std::string code! The char[64]s are allocated once but you reallocate the std::strings every time. By pulling the declaration of s1, s2, and s3 to the top, I'm getting equivalent speed (g++ 4.4.7 with -g, 0.02s each time, clock() isn't any more accurate). And for essentially no runtime cost, you're getting memory safety and exception safety. C++ is all about low-cost abstractions. Any speed difference between the C++ way and the C way should be very small, and the C++ way is safer. Use std::string (and std::vector and all the rest) unless you have a very good reason not too, and then you should probably just write your own custom implementation. Reverting to the C way is just asking for issues.
    - GnarfGnarf 12y ago
      I moved the std::string allocation outside the loop, now it's only ten times slower. I'm all for using abstractions and working smarter, but why pay such a performance penalty?
      - theseoafs 12y ago
        Are you using += like I suggested in my comment?
ma2rten 12y ago
Dropbox seems to be doing ok shipping python to customers.
- koshak 12y ago
  If they were ok why should they had forked python?
PythonicAlpha 12y ago
Might be, but in Python it is much easier to use and better integrated in the language basics. Operator overloading is something, that belongs to the 'pro' skill-set of C++ developers and done wrong, can lead to many problems. In Python it is much easier to overwrite the behavior of such standard methods and the language core can be learned in about 1/4 of the time you need to learn in C++ to just know the basics (C core, C++ object basics, Operator overloading, standard library basics like the string class, ...) -- in Python you get the power with much less learning effort and without the technical troubles.

dkersten 12y ago

I've often heard it said that if you're not using std::string for strings in C++, you're (arguably) not using C++

GnarfGnarf 12y ago
I just did a test using std:: and old-fashioned char[]. The fancy std:: is fifteen times slower than the strcat(). In a loop with intensive string manipulation, this could cause the program to get back to you in 15 seconds instead of 1 second. You don't mind waiting? Here's the code (Visual Studio 2010): #include <string> #include <time.h> char buf[64], buf2[64]; clock_t start = clock(); for(i = 0; i < 100000; i++) { _snprintf(buf, sizeof(buf), "%d", i); _snprintf(buf2, sizeof(buf2), "%d", i * i); #if defined FAST strcat(buf, buf2); #else std::string s1 = buf; std::string s2 = buf2; std::string s3 = s1 + s2; #endif } _snprintf(buf, sizeof(buf), "%.4f\n", (float)(clock() - start) / (float)CLK_TCK); OutputDebugString(buf);
- theseoafs 12y ago
  You should be using `+=` to build strings incrementally in C++, not using `+` repeatedly.
- 30thElement 12y ago
  Well of course you're getting a speed difference, look at how much extra work you're doing in the std::string code! The char[64]s are allocated once but you reallocate the std::strings every time. By pulling the declaration of s1, s2, and s3 to the top, I'm getting equivalent speed (g++ 4.4.7 with -g, 0.02s each time, clock() isn't any more accurate). And for essentially no runtime cost, you're getting memory safety and exception safety. C++ is all about low-cost abstractions. Any speed difference between the C++ way and the C way should be very small, and the C++ way is safer. Use std::string (and std::vector and all the rest) unless you have a very good reason not too, and then you should probably just write your own custom implementation. Reverting to the C way is just asking for issues.
  - GnarfGnarf 12y ago
    I moved the std::string allocation outside the loop, now it's only ten times slower. I'm all for using abstractions and working smarter, but why pay such a performance penalty?
    - theseoafs 12y ago
      Are you using += like I suggested in my comment?

ma2rten 12y ago

Dropbox seems to be doing ok shipping python to customers.

koshak 12y ago
If they were ok why should they had forked python?

PythonicAlpha 12y ago

Might be, but in Python it is much easier to use and better integrated in the language basics. Operator overloading is something, that belongs to the 'pro' skill-set of C++ developers and done wrong, can lead to many problems. In Python it is much easier to overwrite the behavior of such standard methods and the language core can be learned in about 1/4 of the time you need to learn in C++ to just know the basics (C core, C++ object basics, Operator overloading, standard library basics like the string class, ...) -- in Python you get the power with much less learning effort and without the technical troubles.