为什么我在尝试使用打开文件时收到字符串的 C2440 错误<netcdf>图书馆？</netcdf>

Question

I am trying to read a.netCDF file with the library in C++. However, I am getting a C2440 error, telling me that I cannot convert the type of the dataFile to the dataVar. Or, at least this is what I think it is telling me because the compiler error seems a little cryptic to read.

Here is my code:

//create a test object to open netcdf file 
    const std::vector<std::string> path = obj.getPaths(); //returns all paths in the netcdf directory
    const std::string test = path[0]; //gives me a test path that is element 1 in the path vector

    netCDF::NcFile dataFile(test, netCDF::NcFile::read);
    netCDF::NcVar dataVar = dataFile.getVars();

error:

Error C2440 'initializing': cannot convert from 'std::multimap<std::string,netCDF::NcVar,std::less<Aws::String>,std::allocator<std::pair<conststd::string,netCDF::NcVar>>>' to 'netCDF::NcVar' count-lightning C:\Users\Corey4005\Desktop\Dev\projects\count-lightning\src\main.cpp 59  

What should I do to make this code work?

Thanks for the help!

What I have tried:

I tried to open a.netcdf file using the NcFile stream. The NcFile stream takes the following arguments:

netCDF::NcFile dataFile(const std::string &filePath, netCDF::NcFile::fileMode fMode); 

When I provided a string literal to the filePath argument, I received a C2440 'initializing' error. I am confused because I think I am correctly passing a const string literal to a const string argument.

Answer 1

netCDF::NcVar dataVar is a single variable, dataFile.getVars() returns multiple variables in a map. The simplest fix is to use:

auto dataVar = dataFile.getVars();

Or:

std::multimap< std::string, NcVar > dataVar = dataFile.getVars();

If you actually wanted to get a single variable you need to provide a name:

netCDF::NcVar dataVar = dataFile.getVar("myvar");

Seehttp://unidata.github.io.netcdf-cxx4/clas.netCDF_1_1NcFile.html