Structures

by Matthew Martin

Structures are part of the C programming language but can also be used in C++. The only difference is that in C++ structures are treated as a class with all its members being public by default, although it is possible to make them private by using the private keyword in the declaration.

Content

Declaring A Structure

Differences Between Structures In C And C++

Arrays Of Structures

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Declaring A Structure

Structures are declared using the keyword struct. This is done using the following syntax:

struct struct-name: inheritance-list {
//public members by default
…
}object-list;

e.g.:
struct studentrecord {
int codenumber;
char firstname[10];
char lastname[15];
char malefemale;
bool registered;
}

In the above example the structure is called studentrecord and it contains the integer codenumber, two char arrays (strings), a char variable and a Boolean variable.

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Differences Between Structures In C And C++

In C there are no classes, so structures are treated as a special grouping of variables. In C structures can only contain data members, there can be no functions. There is no such thing as encapsulation in C, so effectively everything is public.

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Arrays Of Structures

It is possible to declare arrays of structures. The syntax is:

struct struct-name {
//members
…
} struct-array-name[n];

Using the example of the studentrecord structure from above, an array using this structure can be declared for 100 students, called students:

e.g.:
struct studentrecord {
int codenumber;
char firstname[10];
char lastname[15];
char malefemale;
bool registered;
} students[100];

Sometimes an array of structures is referred to as a structural-array.

by Matthew Martin