What do you mean by passing an array to a function?
Generally we pass values and  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables while  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables a function, likewise we can also  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables arrays to a  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables. You can pass array’s  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables as well as whole array (by just specifying the array name, which works as a pointer) to a  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables.

What is pointer to array?
Array elements can be  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables and manipulated using pointers in C. Using  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables you can easily handle  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables. You can have access of all the  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables of an array just by assigning the array’s base address to  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables variable.

How to store user input data into 2D array
We can calculate how many elements a two  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables array can have by using this formula:
The  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables arr[n1][n2] can have n1*n2 elements. The  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables that we have in the example below is having the  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables 5 and 4. These dimensions are known as  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables. So this  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables has first subscript value as 5 and  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables subscript value as 4.
So the  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables abc[5][4] can have 5*4 = 20 elements.

How to pass an entire array to a function as an argument?
In the above example, we have  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables the  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables of each array element one by one using a for  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables in C. However you can also pass an entire array to a  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables like this:
Note: The  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables name itself is the  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables of first element of that  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables. For example if array name is arr then you can say that arr is equivalent to the &arr[0].

What do you mean by Passing array to function using call by reference?
When we pass the  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables of an array while calling a  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables then this is called function call by  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables. When we pass an  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables as an argument, the function  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables should have a pointer as a  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables to receive the passed  accessedaddressarraycallingdeclarationdimensionaldimensionselementelementsfunctionloopparameterpasspassedpointerpointersreferencesecondsubscriptsvariables.