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Function Overloading,Inline Function and Recursion in C++ By Faisal Shahzad

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Faisal Shehzad

The document discusses three topics: 1) Function overloading in C++ allows functions to have the same name but different parameters. It provides an example demonstrating overloading. 2) Inline functions can reduce function call overhead by expanding the function code at each call site. It discusses the advantages and disadvantages of inline functions and provides an example. 3) Recursion is when a function calls itself directly or indirectly. It requires a base case condition to terminate, otherwise a stack overflow may occur. It provides an example to calculate factorials recursively.

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ASSIGNMENT NO: SUBJECT NAME: TOPIC: Function Overloading in C++ and Its Example Inline Function in C++ and Its Example Recursion in C++ and Its Example SUBMITTED TO: SIR RAO TOUSEEF SUBMITTED BY: Faisal Shehzad ROLL: NO: SP17-MCS-020 SECTION: MCS-B12-A COMSATS Institute of Information Technology Vehari Campus 15-May-2017Date:
Function Overloading in C++ Function overloading is a feature in C++ where two or more functions can have the same name but different parameters. Function overloading can be considered as an example of polymorphism feature in C++. Advantages :-  Overloaded methods give programmers the flexibility to call a similar method for different types of data.  Function overloading is done for code reusability, to save efforts, and also to save memory. Disadvantages :-  There aren’t many notable disadvantages of using function overloading in c++. Following is a simple C++ example to demonstrate function overloading. #include <iostream> using namespace std; void print(int i) { cout << " Here is int " << i << endl; } void print(double f) { cout << " Here is float " << f << endl; } void print(char* c) { cout << " Here is char* " << c << endl; } int main() { print(10); print(10.10); print("ten"); return 0; } The output of following code is shown in the figure.
Following is a simple C++ example to demonstrate function overloading. #include <iostream> using namespace std; void display(int); void display(float); void display(int, float); int main() { int a = 5; float b = 5.5; display(a); display(b); display(a, b); return 0; } void display(int var) { cout << "Integer number: " << var << endl; } void display(float var) { cout << "Float number: " << var << endl; } void display(int var1, float var2) { cout << "Integer number: " << var1; cout << " and float number:" << var2; } The output of following code is shown in the figure. Inline Functions in C++ Inline function is one of the important feature of C++. So, let’s first understand why inline functions are used and what is the purpose of inline function? When the program executes the function call instruction the CPU stores the memory address of the instruction following the function call, copies the arguments of the function on the stack and finally transfers control to the specified function. The CPU then executes the function code, stores the function
return value in a predefined memory location/register and returns control to the calling function. This can become overhead if the execution time of function is less than the switching time from the caller function to called function (callee). For functions that are large and/or perform complex tasks, the overhead of the function call is usually insignificant compared to the amount of time the function takes to run. However, for small, commonly-used functions, the time needed to make the function call is often a lot more than the time needed to actually execute the function’s code. This overhead occurs for small functions because execution time of small function is less than the switching time. C++ provides an inline functions to reduce the function call overhead. Inline function is a function that is expanded in line when it is called. When the inline function is called whole code of the inline function gets inserted or substituted at the point of inline function call. This substitution is performed by the C++ compiler at compile time. Inline function may increase efficiency if it is small. Remember, inlining is only a request to the compiler, not a command. Compiler can ignore the request for inlining. Compiler may not perform inlining in such circumstances like: 1) If a function contains a loop. (for, while, do-while) 2) If a function contains static variables. 3) If a function is recursive. 4) If a function return type is other than void, and the return statement doesn’t exist in function body. 5) If a function contains switch or goto statement. Inline functions provide following advantages: 1) Function call overhead doesn’t occur. 2) It also saves the overhead of push/pop variables on the stack when function is called. 3) It also saves overhead of a return call from a function. 4) When you inline a function, you may enable compiler to perform context specific optimization on the body of function. Such optimizations are not possible for normal function calls. Other optimizations can be obtained by considering the flows of calling context and the called context. 5) Inline function may be useful (if it is small) for embedded systems because inline can yield less code than the function call preamble and return. Inline function disadvantages: 1) The added variables from the inlined function consumes additional registers, After in-lining function if variables number which are going to use register increases than they may create overhead on register variable resource utilization. This means that when inline function body is substituted at the point of
function call, total number of variables used by the function also gets inserted. So the number of register going to be used for the variables will also get increased. So if after function inlining variable numbers increase drastically then it would surely cause an overhead on register utilization. 2) If you use too many inline functions then the size of the binary executable file will be large, because of the duplication of same code. 3) Too much inlining can also reduce your instruction cache hit rate, thus reducing the speed of instruction fetch from that of cache memory to that of primary memory. 4) Inline function may increase compile time overhead if someone changes the code inside the inline function then all the calling location has to be recompiled because compiler would require to replace all the code once again to reflect the changes, otherwise it will continue with old functionality. 5) Inline functions may not be useful for many embedded systems. Because in embedded systems code size is more important than speed. Following is a simple C++ example to demonstrate Inline function. #include <iostream> using namespace std; class operation { int a,b,add,sub,mul; float div; public: void get(); void sum(); void difference(); void product(); void division(); }; inline void operation :: get() { cout << "Enter first value:"; cin >> a; cout << "Enter second value:"; cin >> b; } inline void operation :: sum()
{ add = a+b; cout << "Addition of two numbers: " << a+b << "n"; } inline void operation :: difference() { sub = a-b; cout << "Difference of two numbers: " << a-b << "n"; } inline void operation :: product() { mul = a*b; cout << "Product of two numbers: " << a*b << "n"; } inline void operation ::division() { div=a/b; cout<<"Division of two numbers: "<<a/b<<"n" ; } int main() { cout << "Program using inline functionn"; operation s; s.get(); s.sum(); s.difference(); s.product(); s.division(); return 0; } The output of following code is shown in the figure. Recursion What is Recursion? The process in which a function calls itself directly or indirectly is called recursion and the corresponding function is called as recursive function. Using recursive algorithm, certain problems can be solved quite easily.
What Is Base ConditionIn Recursion? In recursive program, the solution to base case is provided and solution of bigger problem is expressed in terms of smaller problems. intfact(intn) { if (n < = 1) // base case return 1; else return n*fact(n-1); } In the above example, base case for n < = 1 is defined and larger value of number can be solved by converting to smaller one till base case is reached. Why Stack Overflow Error Occurs In Recursion? If base case is not reached or not defined, then stack overflow problem may arise. Let us take an example to understand this. int fact(int n) { // wrong base case (it may cause // stack overflow). if (n == 100) return 1; else return n*fact(n-1); } Let us take the example how recursion works by taking a simple function. /* Example Program For Factorial Value Using Recursion In C++ */ #include<iostream> #include<conio.h> using namespace std; //Function long factorial(int); int main() { // Variable Declaration int counter, n; // Get Input Value cout<<"Enter the Number :"; cin>>n; // Factorial Function Call
cout<<n<<" Factorial Value Is "<<factorial(n); // Wait For Output Screen getch(); return 0; } // Factorial recursion Function long factorial(int n) { if (n == 0) return 1; else return(n * factorial(n-1)); } The output of following code is shown in the figure.

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Function Overloading,Inline Function and Recursion in C++ By Faisal Shahzad

  • 1. ASSIGNMENT NO: SUBJECT NAME: TOPIC: Function Overloading in C++ and Its Example Inline Function in C++ and Its Example Recursion in C++ and Its Example SUBMITTED TO: SIR RAO TOUSEEF SUBMITTED BY: Faisal Shehzad ROLL: NO: SP17-MCS-020 SECTION: MCS-B12-A COMSATS Institute of Information Technology Vehari Campus 15-May-2017Date:
  • 2. Function Overloading in C++ Function overloading is a feature in C++ where two or more functions can have the same name but different parameters. Function overloading can be considered as an example of polymorphism feature in C++. Advantages :-  Overloaded methods give programmers the flexibility to call a similar method for different types of data.  Function overloading is done for code reusability, to save efforts, and also to save memory. Disadvantages :-  There aren’t many notable disadvantages of using function overloading in c++. Following is a simple C++ example to demonstrate function overloading. #include <iostream> using namespace std; void print(int i) { cout << " Here is int " << i << endl; } void print(double f) { cout << " Here is float " << f << endl; } void print(char* c) { cout << " Here is char* " << c << endl; } int main() { print(10); print(10.10); print("ten"); return 0; } The output of following code is shown in the figure.
  • 3. Following is a simple C++ example to demonstrate function overloading. #include <iostream> using namespace std; void display(int); void display(float); void display(int, float); int main() { int a = 5; float b = 5.5; display(a); display(b); display(a, b); return 0; } void display(int var) { cout << "Integer number: " << var << endl; } void display(float var) { cout << "Float number: " << var << endl; } void display(int var1, float var2) { cout << "Integer number: " << var1; cout << " and float number:" << var2; } The output of following code is shown in the figure. Inline Functions in C++ Inline function is one of the important feature of C++. So, let’s first understand why inline functions are used and what is the purpose of inline function? When the program executes the function call instruction the CPU stores the memory address of the instruction following the function call, copies the arguments of the function on the stack and finally transfers control to the specified function. The CPU then executes the function code, stores the function
  • 4. return value in a predefined memory location/register and returns control to the calling function. This can become overhead if the execution time of function is less than the switching time from the caller function to called function (callee). For functions that are large and/or perform complex tasks, the overhead of the function call is usually insignificant compared to the amount of time the function takes to run. However, for small, commonly-used functions, the time needed to make the function call is often a lot more than the time needed to actually execute the function’s code. This overhead occurs for small functions because execution time of small function is less than the switching time. C++ provides an inline functions to reduce the function call overhead. Inline function is a function that is expanded in line when it is called. When the inline function is called whole code of the inline function gets inserted or substituted at the point of inline function call. This substitution is performed by the C++ compiler at compile time. Inline function may increase efficiency if it is small. Remember, inlining is only a request to the compiler, not a command. Compiler can ignore the request for inlining. Compiler may not perform inlining in such circumstances like: 1) If a function contains a loop. (for, while, do-while) 2) If a function contains static variables. 3) If a function is recursive. 4) If a function return type is other than void, and the return statement doesn’t exist in function body. 5) If a function contains switch or goto statement. Inline functions provide following advantages: 1) Function call overhead doesn’t occur. 2) It also saves the overhead of push/pop variables on the stack when function is called. 3) It also saves overhead of a return call from a function. 4) When you inline a function, you may enable compiler to perform context specific optimization on the body of function. Such optimizations are not possible for normal function calls. Other optimizations can be obtained by considering the flows of calling context and the called context. 5) Inline function may be useful (if it is small) for embedded systems because inline can yield less code than the function call preamble and return. Inline function disadvantages: 1) The added variables from the inlined function consumes additional registers, After in-lining function if variables number which are going to use register increases than they may create overhead on register variable resource utilization. This means that when inline function body is substituted at the point of
  • 5. function call, total number of variables used by the function also gets inserted. So the number of register going to be used for the variables will also get increased. So if after function inlining variable numbers increase drastically then it would surely cause an overhead on register utilization. 2) If you use too many inline functions then the size of the binary executable file will be large, because of the duplication of same code. 3) Too much inlining can also reduce your instruction cache hit rate, thus reducing the speed of instruction fetch from that of cache memory to that of primary memory. 4) Inline function may increase compile time overhead if someone changes the code inside the inline function then all the calling location has to be recompiled because compiler would require to replace all the code once again to reflect the changes, otherwise it will continue with old functionality. 5) Inline functions may not be useful for many embedded systems. Because in embedded systems code size is more important than speed. Following is a simple C++ example to demonstrate Inline function. #include <iostream> using namespace std; class operation { int a,b,add,sub,mul; float div; public: void get(); void sum(); void difference(); void product(); void division(); }; inline void operation :: get() { cout << "Enter first value:"; cin >> a; cout << "Enter second value:"; cin >> b; } inline void operation :: sum()
  • 6. { add = a+b; cout << "Addition of two numbers: " << a+b << "n"; } inline void operation :: difference() { sub = a-b; cout << "Difference of two numbers: " << a-b << "n"; } inline void operation :: product() { mul = a*b; cout << "Product of two numbers: " << a*b << "n"; } inline void operation ::division() { div=a/b; cout<<"Division of two numbers: "<<a/b<<"n" ; } int main() { cout << "Program using inline functionn"; operation s; s.get(); s.sum(); s.difference(); s.product(); s.division(); return 0; } The output of following code is shown in the figure. Recursion What is Recursion? The process in which a function calls itself directly or indirectly is called recursion and the corresponding function is called as recursive function. Using recursive algorithm, certain problems can be solved quite easily.
  • 7. What Is Base ConditionIn Recursion? In recursive program, the solution to base case is provided and solution of bigger problem is expressed in terms of smaller problems. intfact(intn) { if (n < = 1) // base case return 1; else return n*fact(n-1); } In the above example, base case for n < = 1 is defined and larger value of number can be solved by converting to smaller one till base case is reached. Why Stack Overflow Error Occurs In Recursion? If base case is not reached or not defined, then stack overflow problem may arise. Let us take an example to understand this. int fact(int n) { // wrong base case (it may cause // stack overflow). if (n == 100) return 1; else return n*fact(n-1); } Let us take the example how recursion works by taking a simple function. /* Example Program For Factorial Value Using Recursion In C++ */ #include<iostream> #include<conio.h> using namespace std; //Function long factorial(int); int main() { // Variable Declaration int counter, n; // Get Input Value cout<<"Enter the Number :"; cin>>n; // Factorial Function Call
  • 8. cout<<n<<" Factorial Value Is "<<factorial(n); // Wait For Output Screen getch(); return 0; } // Factorial recursion Function long factorial(int n) { if (n == 0) return 1; else return(n * factorial(n-1)); } The output of following code is shown in the figure.