Cannot convert std::stringstream to const char*

Question

I tried to run command with help of system() function, forwarding argument as in code below:

std::stringstream volume_control;
int volume_value = 5;
volume_control << "/usr/bin/amixer cset numid=1 " << volume_value << std::endl;
system(volume_control.str());

It doesn't work, because of unsuccessful conversion of std::stringstream to const char*.

I know that in std::string case I have method std::c_string() and If I'm right it returns exactly what I need const char* type, but in this case of stringstream that method does not exist. So what to do?

score 4 · Answer 1 · answered Sep 03 '15 at 12:09

4

volume_control.str() returns a std::string type. You need to call std::string::c_str() or std::string::data() method on it.

A google search would have easily given you the answer.

system(volume_control.str().c_str());

answered Sep 03 '15 at 12:09

Shreevardhan

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Your answer is wrong, see https://stackoverflow.com/a/1374485 for details. – yaskovdev Dec 22 '21 at 13:22

ForEveR · Answer 2 · 2015-09-03T12:06:14.637

0

You should use c_str method on string returned from str method.

system(volume_control.str().c_str());

edited Sep 03 '15 at 12:06

answered Sep 03 '15 at 12:05

ForEveR

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@ForEveR Oops, you are right! The linked case was a different issue! Sorry & thanks! – TrueY Sep 09 '15 at 08:23

score 0 · Answer 3 · answered Sep 23 '20 at 12:43

0

You can refer to this link stringstream, string, and char* conversion confusion

{ const std::string& tmp = stringstream.str(); const char* cstr = tmp.c_str(); }

answered Sep 23 '20 at 12:43

amit wadekar

1

Cannot convert std::stringstream to const char*

3 Answers3