When input is not a or b or c it should get input again. please help me solve it

Question

while( (box != 'a')| (box != 'b')|(box != 'c' )){
printf("please enter a correct name of box ");
scanf(" %c", &box);

}

Answer 1

Try to use && in between the expressions instead. Not sure what you're trying to do here cause it's only a partial code,

Answer 2

Try loop with if condition

While(...)
{
If (your expression with or operator)
Statements

Else
Scanf();

}