CODEWITHSUNDEEP
c++windowspath
JDiMatteo
JDiMatteo

Reputation: 13130

How to run an executable with spaces using std::system on Windows

How can an executable with spaces be run using std::system on Windows without using C++11?

I've tried the seemingly obvious placing quotes around the path with spaces, but in the console window that pops up running the command I get a message that indicates that the full executable path is being split on spaces. For example, I've tried the following:

#include <cstdlib>

int main()
{
    int no_spaces_forward_rc = std::system("c:/IronPython2.7/ipy -c \"print 'no_spaces_forward'\"");
    // no_spaces_forward_rc is 0 and "no_spaces_forward" is written to console window

    int spaces_forward_rc    = std::system("\"c:/Program Files (x86)/IronPython 2.7/ipy\" -c \"print 'spaces_forward'\"");
    // spaces_forward_rc is 1, and "'c:/Program' is not recognized as an internal or external command, operable program or batch file." is written to console window

    int no_spaces_backward_rc = std::system("c:\\IronPython2.7\\ipy -c \"print 'no_spaces_backward'\"");
    // no_spaces_backward_rc is 0 and "no_spaces_backward" is written to console window

    int spaces_backward_rc    = std::system("\"c:\\Program Files (x86)\\IronPython 2.7\\ipy\" -c \"print 'spaces_backward'\"");
    // spaces_backward_rc is 1, and "'c:\Program' is not recognized as an internal or external command, operable program or batch file." is written to console window

    int no_spaces_double_backward_rc = std::system("c:\\\\IronPython2.7\\\\ipy -c \"print 'no_spaces_double_backward'\"");
    // no_spaces_double_backward_rc is 0, and no_spaces_double_backward is written to console window

    int spaces_double_backward_rc    = std::system("\"c:\\\\Program Files (x86)\\\\IronPython 2.7\\\\ipy\" -c \"print 'spaces_double_backward'\"");
    // spaces_double_backward_rc is 1, and "'c:\\Program' is not recognized as an internal or external command, operable program or batch file." is written to console window

    int spaces_double_double_backward_rc    = std::system("\\\"c:\\\\Program Files (x86)\\\\IronPython 2.7\\\\ipy\\\" -c \"print 'spaces_double_double_backward'\"");
    // spaces_dobule_double_backward_rc is 1, and "'\"c:\\Program Files (x86)\\IronPython 2.7\\ipy\"' is not recognized as an internal or external command, operable program or batch file." is written to console window

    return 0;
}

I've verified that running "c:\Program Files (x86)\IronPython 2.7\ipy" -c "print 'spaces_backward'" directly in a cmd prompt works, and I'm pretty sure I don't just have a typo. This is driving me nuts -- any help would be greatly appreciated!

(I'm using Visual Studio 2012 and compiling with subsystem Console if that helps.)

Upvotes: 6

Views: 5591

Answers (3)

Turktle
Turktle

Reputation: 1

For convenience, I wrote a little class command that encapsulates Harry Johnston's solution and makes using system for quoted paths spaces very easy.

Usage:

ifs::win::command c;
std::filesystem::path source = "c:\\my folder\\file.txt";
std::filesystem::path destination = "c:\\another folder\\another file.txt";
try {
    c << "copy " << source << " " << destination;
    c.run();
}
catch (ifs::win::cmd_error& e) {
    std::cout << "command: " << e.command() << std::endl;
    std::cout << "result: " << e.res() << std::endl;
    std::cout << "default error message: " << e.what() << std::endl;
}

Get ifs_win.h/cpp from this repo.

(There is also std::string runAndGetOutput();)

Tested with c++17 on Win10 and Win11.

Upvotes: 0

Harry Johnston
Harry Johnston

Reputation: 36328

The syntax for cmd.exe has a nasty twist. From cmd.exe /?:

1.  If all of the following conditions are met, then quote characters
    on the command line are preserved:

    - no /S switch
    - exactly two quote characters
    - no special characters between the two quote characters,
      where special is one of: &<>()@^|
    - there are one or more whitespace characters between the
      two quote characters
    - the string between the two quote characters is the name
      of an executable file.

To make the behaviour consistent, the std::system call should use the /S switch, and embed the command in quote marks. Sadly, it doesn't. This means that this will work:

std::system("\"c:\\Program Files (x86)\\Adobe\\Reader 10.0\\Reader\\AcroRd32.exe\" h:\\documents\\documentation\\misc\\calendar 1999.pdf");

but this seemingly trivial variant won't:

std::system("\"c:\\Program Files (x86)\\Adobe\\Reader 10.0\\Reader\\AcroRd32.exe\" \"h:\\documents\\documentation\\misc\\calendar 1999.pdf\"");

To fix the problem, the entire command, including the quoted path to the executable, must be surrounded in quotes:

std::system("\"\"c:\\Program Files (x86)\\Adobe\\Reader 10.0\\Reader\\AcroRd32.exe\" \"h:\\documents\\documentation\\misc\\calendar 1999.pdf\"\"");

In your example, that would be

std::system("\"\"c:\\Program Files (x86)\\IronPython 2.7\\ipy\" -c \"print 'spaces_backward'\"\"");

Upvotes: 8

πάντα ῥεῖ
πάντα ῥεῖ

Reputation: 1

OK this code using a raw string literal, actually works for me (VS2013 Express):

std::string cmd = R"cmd("C:\Program Files (x86)\doxygen\bin\doxygen.exe")cmd";
system(cmd.c_str());

For unsupported raw string literals, the traditionally escaped string literal should look as follows 1:

std::string cmd = "\"C:\\Program Files (x86)\\doxygen\\bin\\doxygen.exe\"";

The reason for these double escapings is, that system() actually calls cmd which expects double quotes " enclosing the command line to execute.

1) As easy to see, this is error prone for missing a \ somewhere.

Upvotes: 0

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