Structs

In the C language, there is the struct keyword, for defining a structured chunk of memory.

Example 2.1. src/structdemo/demostruct.h

[ . . . . ]
struct Fraction {
 int numer, denom;
 string description;
};
[ . . . . ]

A structured piece of memory is comprised of smaller chunks of memory of various types and sizes, each chunk accessible by name. Example 2.1 shows the definition of a struct.

Example 2.2 shows how we can use a structured chunk of memory (containing subobjects) as a single entity. Each data member (numer, denom, description) is accessible by name.

Example 2.2. src/structdemo/demostruct.cpp

[ . . . . ]
void printFraction (Fraction f) { <-- 1
 cout << f.numer << "/" << f.denom << endl;
 cout << " =? " << f.description << endl;
}

int main() {

 Fraction f1;

 fl.numer = 4;
 fl.denom = 5;
 fl.description = "four fifths";
 Fraction f2 = {2, 3, "two thirds"}; <-- 2

 f1.numer = f1.numer + 2;
 printFraction (f1);
 printFraction (f2);
 return 0;
}

Output:

 6/5
 =? four fifths
 2/3
 =? two thirds

 

(1)Passing a struct by value could be expensive if it has large components.

(2)member initialization