Difference between class and structure - muneeb-mbytes/computerArchitectureCourse GitHub Wiki

1. Classes can be empty but struct cannot be empty.

output:

2. We must use the keyword ‘new’ while creating objects of a class. This is not required when creating objects of Structs.

Struct creation = class with new()

3. Classes can be inherited but structures cannot.

4. The struct size is the sum of all the elements in struct.

struct{
bit[15:0] salary;
 byte id;
 int abc;
 }employee_s;
 module struct1;
 initial begin 
 employee_s = '{123,25,23};
 $display("size is %d",$bits(employee_s));
 end
 endmodule 

Here if we display the $bits of struct then it will display as 56 because “salary” is 16 bits, id is 8 bits, abc is 32 bits. So the sum is 16+8+32=56.

Output:

for class:

class exam;
    int a=10;
   bit[3:0]b=4'b0001;
   byte c=25;
endclass

exam ex;

module clss;
  initial begin
    ex=new();
    $display("class size is %0d",$bits(ex));
  end
endmodule

Output:

5. Structures have contiguous memory allocation and classes have random memory allocation.