Obtain the list of platforms available.
cl_int clGetPlatformIDs(cl_uint num_entries, cl_platform_id *platforms, cl_uint *num_platforms);
num_entries
The number of cl_platform_id entries that can be added to platforms. If platforms is not NULL, the num_entries must be greater than zero.
platforms
Returns a list of OpenCL platforms found. The cl_platform_id values returned in platforms can be used to identify a specific OpenCL platform. If platforms argument is NULL, this argument is ignored. The number of OpenCL platforms returned is the mininum of the value specified by num_entries or the number of OpenCL platforms available.
num_platforms
Returns the number of OpenCL platforms available. If num_platforms is NULL, this argument is ignored.
Returns CL_SUCCESS if the function is executed successfully. Otherwise it returns CL_INVALID_VALUE if num_entries is equal to zero and platforms is not NULL, or if both num_platforms and platforms are NULL.
Returns CL_OUT_OF_HOST_MEMORY if there is a failure to allocate resources required by the OpenCL implementation on the host.
\m[blue]OpenCL Specification\m[]\s-2\u[1]\d\s+2
clGetPlatformInfo(3clc), clGetDeviceInfo(3clc), classDiagram(3clc)
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OpenCL Specification
page 33, section 4.1 - Querying Platform Info