What is the different between while(0) and while(1) in c language?

Question

While(0) means dont enter into it, but why you want to have while(0) in c code. Any suggestion.

Asked in the interview today.

Answer 1

While(1) is a infinite loop so if you need to come out of it then you need to issue the break statement explicitly.

main()
{
  int i=0;
  while(1) 
  {
    printf("%d\n", i++);
    if (i==2)
      break;
  }
}

While(0) means non entry and code under while will never get executed.

main()
{
  int i=0;
  while(0) 
  {
    printf("%d\n", i++); // This will never get executed 
    if (i==2)
      break;
  }
}

Answer 2

While 0
{
// will never be executed as condition always FALSE
}

While 1
{
// will never given up as condition always TRUE
// this will be used in Multitasking/Threading concepts.
}

Comments

while(0) means the condition will always false and
while(1)means the condition is true

Answer 3

while(0)

Actually While of something (i.e) while( X ) X is the condition we are giving to run the loop for X times, so as we know that in C the value 0 have meaning called FALSE(0x00000000). so whenever a loop receives a FALSE input it will just leave the loop and proceeds with the next immediate statement.

while(1)
looking into While(X), if X = 1, here the value X = 1 will be taken as TRUE (i.e) 0xffffffff, so not only while(1) while (ANY NON ZERO VALUE) can run as infinite loop other than X = 0. simply ,the condition for the loop is always TRUE.
so usually we have to give a condition for the loop to break.

Answer 4

while(1) Is infinite loop & While(0) Do not enter in while loop it directed exit the loop