C++ program won't print anything with vectors?

Question

I compiled my program and run it but nothing happened when I tried to narrow the problem down, it turned out anytime I defined a vector nothing would be sent in the output. In this program, nothing is printed, even the std:cout at the start, and I don't understand how to fix this problem. A simple "hello world" works though. Also, I'm on Windows 10 and use VSCode.

    #include <iostream>
    #include <vector>


    int main( void )
    {
        std::cout << "hello\n";
        std::vector<int> g1; 
    
        for (int i = 1; i <= 5; i++) 
            g1.push_back(i); 
    
        std::cout << "Output of begin and end: "; 
        for (auto i = g1.begin(); i != g1.end(); ++i) 
            std::cout << *i << " "; 
    
        std::cout << "\nOutput of cbegin and cend: "; 
        for (auto i = g1.cbegin(); i != g1.cend(); ++i) 
            std::cout << *i << " "; 
    
        std::cout << "\nOutput of rbegin and rend: "; 
        for (auto ir = g1.rbegin(); ir != g1.rend(); ++ir) 
            std::cout << *ir << " "; 
    
        std::cout << "\nOutput of crbegin and crend : "; 
        for (auto ir = g1.crbegin(); ir != g1.crend(); ++ir) 
            std::cout << *ir << " "; 
    
        return 0; 
    }

In terminal (Windows Powershell) I write this command

g++ test.cpp -o test
.\test

Thank you for answering

the shell doesn't close it just starts waiting for a new command — Luckylone Official, Nov 15 '20 at 13:07
In Windows the compliation result will be saved to `test.exe`. Are there some other executables like `test.bat`, `test.com` in the working directory? — MikeCAT, Nov 15 '20 at 13:09
What's your compiler version? use command "g++ --version' in cmd line — Sambalika, Nov 15 '20 at 13:32
do you have any warning during compilation? Did you already compiled and run a simple "hello world" with this compiler? Try to comment everything after your first cout and compile/run... — Sambalika, Nov 15 '20 at 13:41
I believe It is not a programming issue, but it is a path/enviroment problem. Does `more test.cpp` produce what you expect? Does `ls` produce what you expect? — Askold Ilvento, Nov 15 '20 at 13:41
Did you try to execute your program typing "test" from the related directory but using 'cmd prompt' in place of powel shell? — Sambalika, Nov 15 '20 at 13:47
i get an __gxx_peronality_v0 is unfindable in library dynamic links — Luckylone Official, Nov 15 '20 at 13:51
I tested your code with your compiler on [Techie Delight](https://techiedelight.com/compiler/) and it works fine — Sambalika, Nov 15 '20 at 14:02
In my experience Powershell will **silently suppress errors** arising from missing libraries. You think `g++ test.cpp -o test` succeeds? You better double check that. Because from what I see, it can fail because of missing DLLs and Powershell will happily show you no error message whatsoever. Do you really want to use Powershell as your shell? I don't. — n. m. could be an AI, Nov 15 '20 at 14:07
You may want to read [this](https://stackoverflow.com/questions/23012332/how-to-make-powershell-tell-me-about-missing-dlls). — n. m. could be an AI, Nov 15 '20 at 14:38

score 2 · Answer 1 · answered Nov 15 '20 at 13:29

2

With the same idea as what was advised by Harry. Try to flush systematically after a cout (not doing it may not guaranty the print when you expect it). using << std::endl will end the line and flush the ostream (recomanded after each cout). And if you don't want to end the line use simply << std::flush

answered Nov 15 '20 at 13:29

Sambalika

100
7

2

@LuckyloneOfficial try running it from command prompt instead of powershell. – Everyone Nov 15 '20 at 14:02
2

All files are flushed on program exit anyway. – Surt Nov 15 '20 at 14:36
its not recommended after every single cout, because usually you do not need to flush the stream after each single cout – 463035818_is_not_an_ai Nov 15 '20 at 15:09

score 0 · Answer 2 · answered Nov 15 '20 at 14:03

0

Found answer: turns out you need to put a dll file libstdc++-6.dll into the .exe dir and solved my problem

answered Nov 15 '20 at 14:03

Luckylone Official

31
1

3

That's not a solution, that's a workaround. Take a look at this answer for proper solution: https://stackoverflow.com/a/6405064/6871623 – Everyone Nov 15 '20 at 14:04
@Everyone Static linking is not **the** proper solution. It is **a** solution. It may or may not work for you depending on what exactly you need. – n. m. could be an AI Nov 15 '20 at 14:11
@n.'pronouns'm. What's the proper solution? – Sambalika Nov 15 '20 at 14:12
@n.'pronouns'm. you are correct, not even my method is a proper solution. A proper solution should let the program dynamically link to the standard library and be able to find it. Unfortunately, the author gave us no information as which compiler he's using. This can all be fixed by adding necessary info to environment variables. Without knowing what compiler he's using we can't help much. – Everyone Nov 15 '20 at 14:23
@Everyone: "I write this command `g++ test.cpp -o test`" looks like information about the compiler to me. Perhaps not *complete* information, but quite a lot of it. – Ben Voigt Nov 16 '20 at 00:10
Library files need to be either in the same directory as the .exe, as you did, or, better, in a directory that is referenced in the `PATH` environment variable (for linux, it would be the `LD_LIBRARY_PATH` environment variable). Do you need help editing those? (I wonder why the installer for your compiler did not do that, though.) – Aziuth Nov 16 '20 at 00:11
@BenVoigt that's not any information about the compiler. Different implementations can use the same `g++` name. On Windows, this can be MinGW or Cygwin... – Everyone Nov 16 '20 at 12:58
@everyone: But we know that it isn't cl.exe (Microsoft), or clang, or icc (Intel). Or some obscure compiler, of which there are plenty. Knowing it is GCC (the compiler collection, not the C compiler) is a substantial amount of information. To add to your mingw and cygwin possibilities, it could also be Linux GCC running in a WSL distro. – Ben Voigt Nov 16 '20 at 15:54

C++ program won't print anything with vectors?

2 Answers2

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