C C++ Errors Question:

when u have not declared variable in the main function or
any other function but used in the program.
example:
main()
{
int i,j;----------------> (iSum not declared)
printf("enter the value of i and j");
scanf("%d%d",&i,&j);
iSum = i + j;
printf("The Sum =",iSum);
getch();
}
In this case iSum will Show a compiler error "Variable not
found".