Page 160 - DCAP507_SYSTEM_SOFTWARE

System Software

Notes REG NO. NAMECOURSE TELEPHONE
STDRECà
{ { { {
Field Field Field Field

The type and variable declaration for the above record can be done as follows:
C:
Struct STDREC ] ® Structure-type-identifier
{

int REGNO;
char NAME [15];
char course [8]; ® members
int TELEPHONE;

} SR1, SR2, SR#; ] ® List of structure variables.

ARRAYS

So far, we've been declaring simple variables: the declaration
int i;
declares a single variable, named i, of type int. It is also possible to declare an array of several
elements. The declaration
int a[10];
declares an array, named a, consisting of ten elements, each of type int. Simply speaking, an
array is a variable that can hold more than one value. You specify which of the several values
you're referring to at any given time by using a numeric subscript. (Arrays in programming are
similar to vectors or matrices in mathematics.)
In C, arrays are zero-based: the ten elements of a 10-element array are numbered from 0 to 9. The
subscript which specifies a single element of an array is simply an integer expression in square
brackets. The first element of the array is a[0], the second element is a[1], etc. You can use these
"array subscript expressions" anywhere you can use the name of a simple variable.

Example:
a[0] = 10;

a[1] = 20;
a[2] = a[0] + a[1];
Notice that the subscripted array references (i.e. expressions such as a[0] and a[1]) can appear on
either side of the assignment operator.
The subscript does not have to be a constant like 0 or 1; it can be any integral expression.

Example: it's common to loop over all elements of an array:

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