admin, Author at SimpleTechTalks

C++11: extern template Explained With Simple Example

In C++11 (Introduction to C++11), extern template is added to optimize the compile time and object size. Earlier C++ compiler (C++ 03) instantiate a template function or class whenever it encounters a fully defined template function or class. If the template is used in multiple files, then compiler must create multiple instances of template function or class only to later discard all the instance but one. This would result in extra compile time and increased object file size. In C++ 03 there was no way to avoid this.

In C++11, extern template feature is introduced to avoid this situation.
Format of extern template is as follows

extern template void DemoTemplateFunction <int> ();
extern template class NUM <type>;

(more…)

Early vs Late Binding using Virtual Table and VPtr

by admin

Early Binding	Late Binding
Happens at compile time.	Happens at run time.
Compiler has all information to invoke correct function version at compile time.	Compiler doesn’t have information to identify correct function version.
Normal function calls are example of Early Binding.	Virtual functions are example of Late Binding.
Functions invoked by object is example of early binding	Functions invoked by pointers can be example of late binding.
Early binding is efficient as no cost paid at run-time for function resolution.	Late Binding is slightly costly as function resolution happens at run time.
Early binding doesn’t provide flexibility of one method multiple interfaces.	Late Binding provide flexibility.
Doesn’t have any virtual table or virtual pointer.	It uses Virtual Table and Virtual Pointer.

(more…)

Virtual Functions in C++ Explained With Simple Example

by admin

A virtual function is a member function which is defined in Base class and redefined by the derived class. “virtual” keyword must be added before the function declaration to define a function virtual. These functions gets inherited by Derived class from Base class and Derived class can choose to provide it’s own definition.
A pure virtual function is a virtual function which has no definition in Base class. Pure virtual function definition is used to ensure all derived class must override the base class function definition.

Normal syntax to define virtual function is as follows:

virtual int samplefun (int x, char c);

(more…)

C++ Casting Operators Explained With Simple Example

by admin

Type casting is the method to convert variable (or expression) of a type to another type. Casting operators are special operators which are used to convert variable of one data type to another data type. Type casting can be done in two ways:

Implicit casting is being done automatically where values are copied to another compatible type. Eg: int to long int or float etc.

Explicit casting is done specifically by the programmer. In C++ there are four types of casting operator available.

(more…)

reinterpret_cast Casting Operator Explained With Simple Example

by admin

This is one of the most complex and dangerous casting operators available in C++. The “reinterpret_cast” operator can convert any type of variable to fundamentally different type. This cast operator can convert an integer to a pointer and so on. This cast operator can also convert variable into totally incompatible type too.

Normal syntax to do reinterpret_cast is as follows:

reinterpret_cast <target-type> (expr)

target-type is the target of the cast whereas expr is being cast into the new target-type.

(more…)

static_cast Casting Operator Explained With Simple Example

by admin

This is the simplest type casting operator available in C++. The “static_cast” operator performs a normal cast. This casting operator is basically a substitute for normal casting operator. “static_cast” operator doesn’t do any runtime checks. Hence programmer should consider whether casting is applicable or not.

Normal syntax to do static_cast is as follows:

static_cast <target-type> (expr)

target-type is the target of the cast whereas expr is being cast into the new target-type.

(more…)

const_cast Casting Operator Explained With Simple Example

by admin

This is one of the most dangerous casting operators. The “const_cast” operator is used to remove the const or volatile property of a variable. The target-type and source-type must be of the same type here.

Normal syntax to do const_cast is as follows:

const_cast <target-type> (expr)

target-type and expr must be of same type pointer or reference.

(more…)

dynamic_cast Casting Operator Explained With Simple Example

by admin

This is one of the most important casting operators. The “dynamic_cast” performs a run-time type casting which also checks the type casting validity. If type casting is done to compatible type then it succeeds else it will throw “bad_cast” exception.

Normal syntax to do dynamic_cast is as follows:

dynamic_cast <target-type> (expr)

where target-type and expr must be of type pointer or reference.

(more…)

Program to Return String Having Frequency Of Each Consecutive Character Followed By the Character

by admin

Given an input string of characters write a function that returns another string that has the frequency of each consecutive character followed by the character itself.
eg:
aabbbbbzzzzzzzzzz — a2b5z10
aaabcdf — a3b1c1d1f1

(more…)

Replace Character of String With Another Character N Place Down the Alphabet

by admin

Given a string ‘s’ and a number ‘n’, write a function that returns a string with each character in s replaced with another character that is ‘n’ positions down the alphabet.

If n is 1, A is replaced with B, B is replaced with C, Z is replaced with A and so on.

If n is 2, A is replaced with C, B is replaced with D, Z is replaced with B and so on.

(more…)