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If-then-else flow diagram A nested if–then–else flow diagram. In computer science, conditionals (that is, conditional statements, conditional expressions and conditional constructs) are programming language constructs that perform different computations or actions or return different values depending on the value of a Boolean expression, called a condition.
In this example, because someCondition is true, this program prints "1" to the screen. Use the ?: operator instead of an if-then-else statement if it makes your code more readable; for example, when the expressions are compact and without side-effects (such as assignments).
The detailed semantics of "the" ternary operator as well as its syntax differs significantly from language to language. A top level distinction from one language to another is whether the expressions permit side effects (as in most procedural languages) and whether the language provides short-circuit evaluation semantics, whereby only the selected expression is evaluated (most standard ...
In other words, someone could interpret the previous statement as being equivalent to either of the following unambiguous statements: if a then { if b then s1 } else s2 if a then { if b then s1 else s2 } The dangling-else problem dates back to ALGOL 60, [1] and subsequent languages have resolved it in various ways.
Python uses the following syntax to express list comprehensions over finite lists: S = [ 2 * x for x in range ( 100 ) if x ** 2 > 3 ] A generator expression may be used in Python versions >= 2.4 which gives lazy evaluation over its input, and can be used with generators to iterate over 'infinite' input such as the count generator function which ...
A label is an explicit name or number assigned to a fixed position within the source code, and which may be referenced by control flow statements appearing elsewhere in the source code. A label marks a position within source code and has no other effect. Line numbers are an alternative to a named label used in some languages (such as BASIC ...
A common idiom encountered in template coding is the "chain of fallback values", as seen in this example: {{{1| {{{url| {{{URL|}}}}} Here, if the first positional parameter is defined, then its value will be used. If it is undefined, then the parameter named url will be checked and if
Technically, Perl does not have a convention for including block comments in source code, but POD is routinely used as a workaround. PHP. PHP supports standard C/C++ style comments, but supports Perl style as well. Python. The use of the triple-quotes to comment-out lines of source, does not actually form a comment. [19]