/* This is a calculator program. It includes header files mouse.h, graphics.h,  winoop.h. You can get these files from attached source zip.*/

#include<conio.h>
#include<mouse.h>
#include<graphics.h>
#include<string.h>
#include<stdlib.h>
#include<winoop.h>

void main()
{
   int gd=0,gm,i,j,answer,flag=0,k;
   char prev='1',current,*ch;
   char *nums[]={" 1 "," 2 "," 3 "," 4 "," 5 "," 6 "," 7 "," 8 "," 9 "," 0 "};
   char *num[]={"1","2","3","4","5","6","7","8","9","0"};
   initgraph(&gd,&gm,"");
   button b[10],add,sub,exit,equal,mul,div,ac;
   textbox t;
   initmouse();
   showmouse();
   t.make(150,50,160);
   for(i=0,j=100;i<10;i++,j+=40)
    b[i].make(j,100,nums[i]);
   add.make(100,150," + ");
   sub.make(140,150," - ");
   equal.make(260,150," = ");
   mul.make(180,150," * ");
   div.make(220,150," / ");
   exit.make(350,400," EXIT ");
   ac.make(300,150," AC ");
   j=0;
   while(1)
    {
        setcolor(WHITE);
        while(!flag)//This while terminates when user is finished inputting a number//i.e. when he presses '+', '-', '*', '/'
        {
            for(i=0;i<10;i++)
            {
                if(b[i].click())
                {
                    t.append(num[i]),j++,k=1;//display the number in textboxbreak;
                }
            }
            if(j==1&&k==1)
                t.write(""),t.append(num[i]);
            if(add.click())
                current='+',flag=1;
            elseif(sub.click())
                current='-',flag=1;
            elseif(equal.click())
                current='=',flag=1;
            elseif(mul.click())
                current='*',flag=1;
            elseif(div.click())
                current='/',flag=1;
            elseif(exit.click())
                flag=2;// flag==2 indicates user wants to exit.elseif(ac.click())
            {
                prev='1';
                t.write("");
            }
            k=0;
        }//End of second while loop//Now Calculate the result.if(flag==2)
            break;//flagg==2, go out of the main loop to exit.if(prev=='1')
            answer=atoi(t.text);
        elseif(prev=='+')
            answer+=atoi(t.text);
        elseif(prev=='-')
            answer-=atoi(t.text);
        elseif(prev=='*')
            answer*=atoi(t.text);
        elseif(prev=='/'&&(atoi(t.text))==0)
            msgbox("Cannot divide by zero"),prev='1',t.write("");
        elseif(prev=='/')
            answer/=atoi(t.text);
        flag=0,j=0;
        prev=current;
        itoa(answer,ch,10);
        t.write(ch);
    }
    closegraph();
}