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Computer Programming Spring-2007

Computer Programming Spring-2007. Union in C language Accessing mouse in C language. Union. As structures, unions are also used to group a number of different variables together .

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Computer Programming Spring-2007

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  1. Computer ProgrammingSpring-2007 Union in C language Accessing mouse in C language

  2. Union • As structures, unions are also used to group a number of different variables together. • The difference between union and structure is that, structure treat each of its member as a different memory location store in the main memory. • While union treat each of its member as a single memory location store in the main memory. • i.e. all of the members of union shares a common memory of union member.

  3. Union Example union searchOption { int SearchByRollNumber; char SearchByName[90]; char SearchByAddress[90]; char SearchByPhoneNumber[90]; }; searchOption sv; void main (void) { int option = 0; switch (option) { case 0: FunSearchRoll (sv.SearchByRollNumber); break; case 1: FunSearchName(sv.SearchByName); break; case 2: FunSearchByAddress(sv.SearchByAddress); break; case 3: FunSearchByPhone(sv.SearchByPhoneNumber); break; } } 90 Bytes

  4. Accessing Mouse in C/C++ • union REGS in,out;       void callmouse(){       in.x.ax=1;       int86(51,&in,&out);} • int86 (…) is declared in the “dos.h” file, so include this file before calling the function.

  5. Accessing Mouse in C/C++ union REGS { struct WORDREGS x; struct BYTEREGS h; } struct WORDREGS { unsigned int ax, bx, cx, dx; }; struct BYTEREGS { unsigned char al, ah, bl, bh; unsigned char cl, ch, dl, dh; };

  6. Accessing Mouse in C/C++ The various mouse functions can be accessed by setting up the AX register with different values (service number) and issuing interrupt number 51.

  7. Accessing Mouse in C/C++

  8. Accessing Mouse in C/C++

  9. Setting Mouse Position •      void setposi(int xpos,int ypos)      {              in.x.ax=4;             in.x.cx=xpos;             in.x.dx=ypos;             int86(51,&in,&out);      }

  10. Receiving Mouse Position and Button Status •        void mouseposi(int *xpos,int *ypos,int *click)       {               in.x.ax=3;              int86(51,&in,&out);              *click=out.x.bx;              *xpos=out.x.cx;              *ypos=out.x.dx;        }

  11. Hiding Mouse •        void mousehide()       {              in.x.ax=2;              int86(51,&in,&out);       }

  12. Final Code void main (void ) {             int xCor,yCor,click,a,b;             a=40*8;  b=12*8;             setposi(a,b);             callmouse();             while (1)             {                    mouseposi(&xCor,&yCor,&click);                    gotoxy(10,9);                    printf("\n\tMouse Position is: %d,%d",xCor/8,yCor/8);                    printf("\n\tClick: %d",click); if ( click == 2 ) break;             }             mousehide();}   

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