The use of atomic weapons at the end of World War 2 fostered fears about their potential use during the Cold War years.
Interrupts and signals are low-level mechanisms that can alter the flow of control in a way similar to a subroutine, but usually occur as a response to some external stimulus or event (that can occur asynchronously), rather than execution of an 'in-line' control flow statement.
C has three kinds of iteration statements. The first is a while-statement with the form. while ( expression ) statement. The substatement of a while runs repeatedly as long as the control expression evaluates to non-zero at the beginning of each iteration.