Convert curl request

_Flaviu

I need to do the following request within a C++ app (response is json):

curl --header "x-api-key:ABCD" -s https://api.test.se/api/mydata

1. Can I replace curl with another protocol ? (This is not mandatory, could be as it is now) 2. Is there a header only c++ lib that can complete this request ? Of course, I know there is REST SDK library, but it is too much trouble for that simple request. Thank you.

k5054

curl isn't a protocol, as such, but a CLI tool for data transfer using urls. The underpinnings are based on libcurl, a C library, that implements the data trasfer. As such, you can make API calls directly from your C++ program. Another option would be to look into popen() e.g.

#include

int main()
{
FILE *pipe = popen("curl --header \"x-api-key:ABCD\" -s https://api.test.se/api/mydata", "r");

while( // read data from **pipe** is true )
{
     // process data
}
fclose(pipe);

}

Keep Calm and Carry On

_Flaviu

Hmm ... I tried:

FILE* pipe = _popen("curl --header \"x-api-key:ABCD\" -s https://api.test.se/api/mydata", "r");

while (true)
{
	pipe->\_Placeholder;
	break;
}

fclose(pipe);

but I cannot retrieved any data from pipe ...

k5054

using a C style FILE * you have to use C stdio functions. So for example you could do

#include
#include

FILE *pipe = popen( ... );

char *buff = NULL;
size_t blen = 0;
while( getline(&buff, &blen, pipe) > 0) {
// process input data in buff;
}
free(buff);

I generally prefer getline() to fgets() when using cstdio because it allocates and grows the input buffer as needed. If you wish to stick with a more C++ style interface, then maybe look into [Boost.Process](https://www.boost.org/doc/libs/1\_79\_0/doc/html/process.html) I think you've mentioned QT as part of your framework, so there's [QProcess](https://doc.qt.io/qt-6/qprocess.html) as well.

Keep Calm and Carry On

Lost User

The pipe returned from _popen is a FILE* so you must read the date from it.

_Flaviu

The C++ app is MFC app ...

k5054

For some reason, I was assuming you were using linux. If you're on windows, there's no getline in the C stdio library, so you'll have to use fgets() or another C stdio FILE i/o function. It might be a better choice to use the libcurl API directly. Or another C/C++ client library. A quick google search turned up [Windows HTTP Services - Win32 apps | Microsoft Docs](https://docs.microsoft.com/en-us/windows/win32/winhttp/winhttp-start-page) , but that appears to be a Win32 API, so may not be applicable to your situation. There's also [GitHub - embeddedmz/httpclient-cpp: C++ client for making simple HTTP requests](https://github.com/embeddedmz/httpclient-cpp) which might work for you too. I have not tried this package, so cannot speak to its quality or suitability for any purpose, what so ever. Caveat usor.

Keep Calm and Carry On

_Flaviu

But there is getline in c++: std::getline - cppreference.com[^] I need to try it, then I'll ocme back wih feedback.

k5054

std::getline() isn't part of C stdio, its part of C++. The getline with the signature int getline(char **, size_t *, FILE *) (i.e C stdio, thus the FILE * parameter) is not provided by MS in the windows C/C++ environment. Or at least it wasn't with VS 2017. It might have been added since then, but I don't think so.

Keep Calm and Carry On

_Flaviu

I have tried:

std::ifstream ifs("curl --header \"x-api-key:ABCD\" -s https://api.test.se/api/mydata");
while (ifs.good())
{
std::string line;
while (std::getline(ifs, line))
{
std::cout << line.c_str() << std::endl;
}
}

Nothing retrieved.

Lost User

std::ifstream reads files, and does not have a constructor which executes an external program. You should go back to pure C and use the _popen function. [edit] This all you need:

char buffer\[132\];
FILE\* pipette = \_popen("curl --header \\"x-api-key:ABCD\\" -s https://api.test.se/api/mydata", "r");
while (fgets(buffer, 132, pipette))
{
    printf("%s", buffer);
}

[/edit]

k5054

Of course not, unless you actually have a file in your current directory called curl --header "x-api-key:ABCD" -s https://api.test.se/api/mydata.

Keep Calm and Carry On

_Flaviu

Yes, that seems to work. Thank you all of you !