can somebody help me in writing a 3d array in which the user defines the size and inputs the data(numbers)???

: can somebody help me in writing a 3d array in which the user defines the size and inputs the data(numbers)???
:
Pascal doesn't allow dynamic arrays, so there will always be a maximum number of elements. Here is an example, which allows the user to specify up to 100x100x100 integers:

var
  UserArray: array[1..100, 1..100, 1..100] of integer;
  UserArraySize: array[1..3];
  X, Y, Z, i, j: integer;
begin 
  { Set Dimensions }
  repeat
    write('Give X size: '); readln(UserArraySize[1]);
  until UserArraySize[1] in [1..100]; { Check the size. }
  repeat
    write('Give Y size: '); readln(UserArraySize[2]);
  until UserArraySize[2] in [1..100]; { Check the size. }
  repeat
    write('Give Z size: '); readln(UserArraySize[3]);
  until UserArraySize[3] in [1..100]; { Check the size. }
  writeln('Select an element to Enter:');
  repeat
    write('X: '); read(X);
  until X in [1..UserArraySize[1]];
  repeat
    write('Y: '); read(Y);
  until Y in [1..UserArraySize[2]];
  repeat
    write('Z: '); read(Z);
  until Z in [1..UserArraySize[3]];
  write('Value for ',X,',',Y,',',Z,':'); readln(UserArray[X, Y, Z]);

  { Code to show 2D-slice of the array}
  for i := 1 to UserArraySize[2] do
  begin
    for j := 1 to UserArraySize[1] do
      write(UserArray[j, i, z]), ' ');
    writeln;
  end;
end.

There are various other ways to structure such an array. One commonly used method utilizes a 1D-array and calculates the 3D-coordinates to a 1D-coordinate. The main advantage is that the dimension-maximums aren't set, only the total number of elements.
Other methods use linked-lists to build the array. The advantage of this is that the array becomes dynamic.
These methods are increasingly harder to code and debug.