expression

What is this smiley-with-beard expression: “”?

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The program uses digraphs to represent the following: [] {}; This is a lambda expression that does nothing. The corresponding symbols have these equivalents: <: = [ %> = } Though they are generally unneeded today, digraphs are useful for when your keyboard lacks certain keys necessary to use C++’s basic source character set, namely … Read more

Combining two expressions (Expression)

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Well, you can use Expression.AndAlso / OrElse etc to combine logical expressions, but the problem is the parameters; are you working with the same ParameterExpression in expr1 and expr2? If so, it is easier: var body = Expression.AndAlso(expr1.Body, expr2.Body); var lambda = Expression.Lambda<Func<T,bool>>(body, expr1.Parameters[0]); This also works well to negate a single operation: static Expression<Func<T, … Read more

What is the difference between an expression and a statement in Python?

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Expressions only contain identifiers, literals and operators, where operators include arithmetic and boolean operators, the function call operator () the subscription operator [] and similar, and can be reduced to some kind of “value”, which can be any Python object. Examples: 3 + 5 map(lambda x: x*x, range(10)) [a.x for a in some_iterable] yield 7 … Read more

Expression Versus Statement

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Expression: Something which evaluates to a value. Example: 1+2/x Statement: A line of code which does something. Example: GOTO 100 In the earliest general-purpose programming languages, like FORTRAN, the distinction was crystal-clear. In FORTRAN, a statement was one unit of execution, a thing that you did. The only reason it wasn’t called a “line” was … Read more