In this post i want to discuss about conditional statement specifically the one without comparison.

as we all know conditional statement is one of very basic logic that oftenly used in many situation, one of the syntax is like this

if(somevariable == somevalue) {
  // doing something
}

This logic usually used to check whether some variable value is equal to expected value or not, thus it also possible to use this to check whether some variable is exists, initialized, defined, or not. for example in javascript if you want to check whether some variable defined or not, you can write something like this:

if(somevariable != undefined){
  // do something
}

Even with most of the high level programming language you can just write something like this

if(somevariable){
  //do something
}

However doing something like above is not recommended, why? depends on what programming language you use, but this statement not only reject undefined or null value, it also reject default value of data type. For example if you wrote code like above example, in javascript if somevarible value is 0 (default value of int) it will rejected by those condition therefor it would not process command inside statement, same thing happened if somevariable value is empty string ''. Sometimes developer not aware about this case where most of the time it will produce some bug to their program.

So here i list some of programming language behaviour with conditional statement without comparison.

Javascript:

if(somevariable) {
  // undefined
  // null
  // 0
  // ''
  // will not process to this
}

Python:

if somevariable:
  # None
  # 0
  # ''
  # []
  # {}
  # will not process to this

So be careful with the usage of this syntax, know your programming language behaviour and you’ll be safe.