Use the calls in the C language
Parameters that are input only and of type MQHCONN, MQHOBJ, MQHMSG, or MQLONG are passed by value. For all other parameters, the address of the parameter is passed by value.
You do not need to specify all parameters that are passed by address every time that you invoke a function. Where we do not need a particular parameter, specify a null pointer as the parameter on the function invocation, in place of the address of parameter data. Parameters for which this is possible are identified in the call descriptions.
No parameter is returned as the value of the call; in C terminology, this means that all calls return void.
Parent topic: Call descriptions