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".