• A programming language construct which stores and organizes a set of data items is called a data structure.
• There are different types of data structures – arrays, stacks, queues, linked lists, structures, trees, files, etc.

• An array can be defined as an ordered list of homogeneous data elements.
• These elements may be of type int, float, char or double.
• All these elemets are stored in consecutive memory locations.
• An array is described by a single name or an identifier.
• And each element in an array is referenced by a subscript(or an index) enclosed in a pair of square brackets.
• The subscript indicates the position of an individual data item in an array.
• The subscipt must be an unsigned positive integer.
• Because of these subscripts, sometimes an array is called as a subscripted variable.

• Arrays classified into – one-dimensional array and multi-dimensional arrays.
• The dimensionality of an array is determined by the number of subscripts present in the given array.
• An array must be declared before it appears in a C program. At the same time, the size of an array must be specified.

• One-dimensional array – This is a linear list of a fixed number of data items of the same type.
• Similar to a row or a coloumn matrix.
• Also called a single-dimensional array or a one-subscripted variable.
• Syntax – data-type arrayname[size];

• Subscript must be an unsigned positive integer constatnt or an expression.
• Subscript of subscript is not allowed.
• C does not perform bounds checking for an array.
• In C, the subscript value ranges from 0 to one less than the maximum size.

• The total amount of memory that can be allocated to a one-dimensional array is computed as -

Total size = size * [sizeof(data_type)];

• Initialization of a one-dimensional aray

Syntax – data_type array_name[size] = {element1,element2,…,elementn};

• Multi-dimensional arrays – If the number of subscripts is more than one then such arrays are called multi-dimensional arrays.
• Two-dimensional(2-D) array, three-dimensional(3-D) array, and so on.

• Two-dimensional array – It is an ordered table of homogeneous elements.
• Generally referred to a matrix of some rows and some coloumns.
• Also called a two-subscripted variable.
• Syntax – data_type array_name[rows][coloumns];
• Row-major order and Coloumn-major order.

• Initialization of a two-dimensional array

Syntax – data_type array_name[size1][size2]={e1,e2,…,en};

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