Imperative versus Declarative Programming

A code example of an imperative language (C-h-) is shown following. This is a function that normalizes a vector according to the Euclidian L -Norm — that is, it divides each component of a vector by the square root of the sum of products of all vector components. 

The function is called with two parameters, one of which is a pointer ( ) to a multidimensional variable (Vector) that represents the input vector that has to be normalized. The other parameter is the length of the vector (N). The code then declares a variable (Norm) and initializes it, or (assigns a start value of zero). It then defines a loop (for statement) that runs over all components (i) of the vector to summarize all component products. It then calculates the square root (sqrt) of the sum. In a second loop, it again runs over all vector components to divide them by the square 

Descriptive Languages Macro Languages, VBA JavaScript, VB, Python, Perl C+ t, C, Java, Python, Perl FORTRAN, Common LLSP, C Assembler 

This is a procedural algorithm that is performed in a sequential manner and leads to an explicit answer. The program code may be called from another code and may include function calls, such as the square root function sqrt. 

Closely related to the latter is declarative programming that describes states rather than how to achieve them. Additionally, the syntax is modeled after the way humans describe a state and thus is more declarative than other languages. 

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