The compilation errors are returned to you in the ppErrorMsgs parameter. It will be in an ID3DXBuffer object, so you just need to call GetBufferPointer and cast the pointer to char* to read it as a string.

HRESULT result;
ID3DXBuffer* errors = NULL;
result = D3DXCompileShaderFromFile( "pixel.psh",	 //filepath
								    NULL,		    //macro's
								    NULL,		    //includes
								    "ps_main",	   //main function
								    "ps_1_1",	    //shader profile
								    0,			   //flags
								    &code,		   //compiled operations
								    &errors,		 //errors
								    NULL);		   //constants
if(FAILED(result)) {
    const char* errstring = "";
    if(errors != NULL)
	    errstring = reinterpret_cast<const char*>(errors->GetBufferPointer());
    printf("failed: %s", errstring);
}

The compilation errors are returned to you in the ppErrorMsgs parameter. It will be in an ID3DXBuffer object, so you just need to call GetBufferPointer and cast the pointer to char* to read it as a string.