1
Chapter 1
C++ Templates
(Sections 1.6, 1.7)
Templates
Type-independent patterns t hat can work with multiple
data types.
Function Templates
These define logic behind the algorithms that work for
multiple data types.
Class Templates
These define generic class patterns into which specific data
types can be plugged in to produce new classes.
Function Templates example
Generic function to find a
maximum value in a given vector
If argument is a vector<int>
type, then compiler generates a
corresponding function which
Comparable is replaced by
vector<int> type.
Similarly for vector<double>,
vector<string> etc.
Assumption in this example:
Operator< is defined in the
Comparable.
Hence assumptions made by the
template much be clearly stated.
Function Templates Usage
Each call to
findMax(Comparabl e a) on
a different data type fo rces the
compiler to generate a different
function using the tem plate.
Compiler will complai n about
findMax(v4) be cause IntCell
class does not define
operator<
Class Template Example
MemoryCell template can be used for
any type Object.
Assumptions
Object has a zero paramet er
constructor
Object has a copy construc tor
Copy-assignment operator
Convention
Class templates declaration and
implementation usually comb ined in a
single file.
It is not easy to separate the m in
independent files due to com plex C++
syntax.
This is different from the con vention of
separating class interface an d
implementation in different fi les.
Class Template Usage Example
MemoryCell can be
used to store both
primitive and class types.
Remember
MemoryCell is not a
class.
It’s a class template.
MemoryCell<int>,
MemoryCell<string>
are classes.
