Object oriented programming using c++
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The document discusses inline functions in C++. It defines inline functions as functions that are treated like macros by having their body substituted at call sites. This avoids overhead from function calls. The document provides an example of an inline square function and discusses advantages like reduced runtime and flexibility. It notes inline functions should have small bodies and only be used for performance optimizations identified via profiling.
Object oriented programming using c++
- 1. TRINITY INSTITUTE OF PROFESSIONAL STUDIESSector – 9, DwarkaInstitutional Area, New Delhi-75 Affiliated Institution of G.G.S.IP.U, Delhi Object Oriented Programming using C++ Paper ID : 20209 Course : BCA InlineFuntions By HimjaSethi Asstt. Prof. (IT)
- 2. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, DwarkaInstitutional Area, New Delhi-75 Inline Functions • A function in C++ can be treated as a macro if the keyword inline precedes its definition • Syntax of representing inline function: inline ReturnType FunctionName(Parameters) { // body of the main function }
- 3. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, DwarkaInstitutional Area, New Delhi-75 Syntax : Inline Function Function to find square of a number : inline float square(float x) { x = x* x; return (x); }
- 4. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, DwarkaInstitutional Area, New Delhi-75 Advantages: Inline Functions • There is no explicit function call; the function body is substituted at the point of inline function call • Runtime overhead for function linkage mechanism is reduced. • The execution time of the function square() is less than the time required to establish a linkage between the function caller and the callee. • Inline functions provide flexibility and benefits of modular programming.
- 5. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, DwarkaInstitutional Area, New Delhi-75 Advantages : Inline Functions • Inline functions provide flexibility and benefits of modular programming. • Provide computational speedups of macros. • It is advisable to define functions having small body as inline functions.
- 6. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, DwarkaInstitutional Area, New Delhi-75 Sample Program #include <iostream.h> inline float square(float x) { x = x* x; return (x); } void main() { float num; cout<<“ Enter a number <float>”; cin>>num; cout<< “Its square = “ << square (num); } Gets replaced by the instructions of square() function body by compiler
- 7. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, DwarkaInstitutional Area, New Delhi-75 Outside Member Functions as Inline • Member functions declared outside the class declaration can be made inline by prefixing the inline to its definition as shown: inline ReturnType ClassName::MemberFunctionName(Argument s ) { … }
- 8. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, DwarkaInstitutional Area, New Delhi-75 When to use inline Functions • In general, inline functions should not be used • If a fully developed and tested program runs too slowly and shows bottlenecks in certain functions then it can be considered to use inline functions. A profiler ( which runs the program and determines where most of the execution time is spent) can be used in deciding such an optimization. • When member functions consist of one very simple statement such as the return statement in the example below: inline int date :: getday() { return day; }
- 9. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, DwarkaInstitutional Area, New Delhi-75 When to use inline Functions • It is only useful to implement an inline function if the time spent during a function call is more compared to the function body execution time. An example where an inline function has no effect at all is the following: inline void date :: show() { cout << day << “ –” << month<< “-” << year << endl; } The above function takes relatively longer time to execute. The effect of conversion of the function show() to inline would lead to reduction in execution time.
- 10. TRINITY INSTITUTE OF PROFESSIONAL STUDIES Sector – 9, DwarkaInstitutional Area, New Delhi-75 Disadvantage of Inline Function • The actual code is inserted by the compiler and therefore it should be known at the compile time. Hence, an inline function can not be located in a run-time library.