0
It's an object of the class ostream.
Wiki User
∙ 10y ago
Add your answer:
Earn +20 pts
How can you use pointers as a function arguments?
You would use a pointer as a parameter when you want to pass the parameter by reference, meaning your function has a reference to the object being passed in, rather than simply a copy of that object. This means that changes to that object made in the function will persist once that function has completed. The below example should print: x = 3 x = 4 Note: I just coded this from memory so you will probably have to tweak it slightly to get it to compile int main() { int x = 3; passByVal(3); cout << "x = " + x; passByRef(3); cout << "x = " + x; return 0; } void passByVal(int a) { a++; // a is a copy of x, a different object } void passByRef(int &b) { b++; // b is a reference to the same object that x points to }
Why Cin and Cout cannot be used outside the main function?
You are completely wrong here.Another answer:There is nothing to say you cannot use cin or coutoutside the main() function (for example, you can use them in a function called from main()). However, using them before main() has been called (e.g. in the constructor of a static object) can have disastrous consequences: cin and cout are themselves static objects, and static initialisation order is undefined. Thus you could be calling them before they have been properly constructed.
What is namespace in c plus plus program?
A namespace is similar to a class in object oriented programming. A namespace contains functions defined by the programmer. for example namespace std contains functions like cout and cin.namespaces can be globaly declared like so: "using namespace std;"which includes all the functions located in the namespace std.if you only need to use cout you can globaly declare only cout like this "using std::cout;"orstd::cout
Syntex for accessing data members of the structure in c plus plus?
Use the member accessor (.) operator. struct object { int m_data; }; int main() { object o; o.m_data = 100; std::cout << o.m_data << std::cout; return(0); }
Is cin a function or object in c?
cin is an object........ An Example is // By Codex #include <iostream> using namespace std; int main(){ int age; cout << "How Old Are You?\n"; cin >> age; cout << "You are << age << years old\n"; system("pause") return 0; }
What is the definition of cout?
COUT is an inbuilt function in c++ language. Cout is used to print something on to the standard output.
What is inventory pointer c?
// Inventory Pointer // Demonstrates returning a pointer #include <iostream> #include <string> #include <vector> using namespace std; //returns a pointer to a string element string * ptrToElement(vector<string>* const pVec, int i); int main() { vector<string> inventory; inventory.push_back( "sword"); inventory.push_back( "armor"); inventory.push_back( "shield"); //displays string object that the returned pointer points to cout << "Sending the objected pointed to by returned pointer:\n"; cout << *(ptrToElement(&inventory, 0)) << "\n\n"; //assigns one pointer to another - inexpensive assignment cout << "Assigning the returned pointer to another pointer.\n"; string* pStr = ptrToElement(&inventory, 1); cout << "Sending the object pointed to by new pointer to cout:\n"; cout << *pStr << "\n\n"; //copies a string object - expensive assignment cout << "Assigning object pointed by pointer to a string object.\n"; string str = *(ptrToElement(&inventory, 2)); cout << "Sending the new string object to cout:\n"; cout << str << "\n\n"; //altering the string object through a returned pointer cout << "Altering an object through a returned pointer.\n"; *pStr = "Healing Potion"; cout << "Sending the altered object to cout:\n"; cout << inventory[1] << endl; return 0; } string * ptrToElement(vector<string>* const pVec, int i) { //returns address of the string in position i of vector that pVec points to return &((*pVec)[i]); }
What is the function of the cin and cout statements?
cin and cout are synonymous with stdin and stdout, implementing console input and output respectively.
Does it matter whether a simple primitive data type like double is being passed or an object is being passed please provide sample code to clarify?
The difference is not so much whether the variable being passed is a primitive or an object (they're both variables after all), but whether the variable is being passed by value or passed by reference.When you pass by value, the variable is automatically copied by the function. If the variable is a complex object, this puts a heavy burden on the function call, consuming more memory on the call stack than might otherwise be necessary, and therefore impacting on performance.Ideally, all user-defined functions should accept a constant reference if the variable will not be altered by the function call. If the function must change the variable, the function should be overloaded to accept a non-constant reference and a non-constant value. In this way, if the changes are expected then the caller can choose to pass by reference. But if the caller does not want the original value to change they can pass by value instead. This is the same as making a copy of the object and passing the copy by reference, but if you don't actually need the copy when the function returns, the call by value function will create and destroy the copy for you, making your calling code that little bit cleaner.The following code demonstrates the difference between calling by reference and calling by value. Pay particular attention to the call by value on the object which calls the object's copy constructor. The same happens to the primitive (an integer) hence the memory address changes within the function, but as it's length is no worse than that of a pointer this isn't a major problem.Note that pointer variables are always passed by value (that is, the address they contain is passed, not the pointer itself). To pass a pointer by non-constant reference you must pass a pointer-to-pointer instead. The pointer-to-pointer is still passed by value, but the memory address it contains is a reference to the actual pointer -- which can then be manipulated by the function.#include using namespace std;class Simple{public:Simple():m_iVar( 20 ), m_cVar('X'){ cout
What is inventory referencer c plus plus?
// Inventory Referencer // Demonstrates returning a reference #include <iostream> #include <string> #include <vector> using namespace std; //returns a reference to a string string & refToElement(vector<string>& vec, int i); int main() { vector<string> inventory; inventory.push_back( "sword"); inventory.push_back( "armor"); inventory.push_back( "shield"); //displays string that the returned reference refers to cout << "Sending the returned reference to cout:\n"; cout << refToElement(inventory, 0) << "\n\n"; //assigns one reference to another - inexpensive assignment cout << "Assigning the returned reference to another reference.\n"; string& rStr = refToElement(inventory, 1); cout << "Sending the new reference to cout:\n"; cout << rStr << "\n\n"; //copies a string object - expensive assignment cout << "Assigning the returned reference to a string object.\n"; string str = refToElement(inventory, 2); cout << "Sending the new string object to cout:\n"; cout << str << "\n\n"; //altering the string object through a returned reference cout << "Altering an object through a returned reference.\n"; rStr = "Healing Potion"; cout << "Sending the altered object to cout:\n"; cout << inventory[1] << endl; return 0; } //returns a reference to a string string & refToElement(vector<string>& vec, int i) { return vec[i]; }
Compare call by value and call by reference with an example?
Call by value passes a copy of the argument into the function parameter while call by reference passes the argument itself. Call by value automatically copies the argument, thus if the argument is a complex object, the object's copy constructor will be called. The following example demonstrates the difference. Note that call by value calls the copy constructor but call by reference does not. Since call by value works on a copy of the object, the original object is left unaffected. However call by reference can mutate the object. #include <iostream> class object { public: object(int data):m_data(data){} object(const object& rhs):m_data(rhs.m_data){std::cout << "Copying" << std::endl;} int get_data()const{return(m_data);} void set_data(int data){m_data=data;} private: int m_data; }; void byVal(object o) { o.set_data(1); } int byRef(object& o) { o.set_data(1); } int main{ object a(0); std::cout << "a is " << a.get_data() << std::endl; std::cout << "Calling by value" << std::endl; byValue(a); std::cout << "a is " << a.get_data() << std::endl; std::cout << "Calling by reference" << std::endl; byRef(a); std::cout << "a is " << a.get_data() << std::endl; return( 0 ); } Output: a is 0 Calling by value Copying a is 0 Calling by reference a is 1
How do you make a calculator using switch statement?
In C++: #include <iostream> using namespace std; int main() { int x, y; char func; cout << "Enter a number: "; cin >> x; cout << "Choose Function: "; cin >> func; cout << "Enter another number: "; cin >> y; switch(func) { case '+': cout << x + y << endl; break; case '-': cout << x - y << endl; break; case '*': cout << x * y << endl; break; case '/': cout << x / y << endl; break; default: cout << "Invalid Function!" << endl; break; } char wait; cin >> wait; return 0; }
How can you use pointers as a function arguments?
You would use a pointer as a parameter when you want to pass the parameter by reference, meaning your function has a reference to the object being passed in, rather than simply a copy of that object. This means that changes to that object made in the function will persist once that function has completed. The below example should print: x = 3 x = 4 Note: I just coded this from memory so you will probably have to tweak it slightly to get it to compile int main() { int x = 3; passByVal(3); cout << "x = " + x; passByRef(3); cout << "x = " + x; return 0; } void passByVal(int a) { a++; // a is a copy of x, a different object } void passByRef(int &b) { b++; // b is a reference to the same object that x points to }
How do you pass object as fuction arguments explain with example in oops?
Objects are normally passed by reference or by pointer. The only difference is that a pointer may be NULL but a reference can never be NULL. You may also pass by value, but when you do this the object is automatically copied, thus any changes made by the function are not reflected in the original object. Passing large and complex objects by value is detrimental to performance and should only be done when you do not wish changes to be reflected in the original value (alternatively, you may copy the value before making the call and pass the copy by reference). Passing by constant reference ensures no changes are made to the immutable members of the original object. In the following example, a simple class is defined with one data member (an int) and two methods, Increment and Print. Three functions are defined to accept objects of the class, by reference, by pointer and by value. All three call the object's Increment function. The main() function instantiates an object of the class and passes the object to those three functions in turn. Note how pass by value automatically calls the copy constructor, incrementing the copy but not the original object. Note also that the copy constructor accepts a constant reference since no changes are expected when copying an object. #include <iostream> using namespace std; class MyClass { public: // construction MyClass():m_data(0){} MyClass(const MyClass & object):m_data(object.m_data){cout << "(Copying) "; } public: // methods void Increment(){++m_data;} void Print(){cout << m_data << endl; } private: int m_data; }; void ByRef(MyClass & object) { object.Increment(); } void ByPointer(MyClass * pointer) { if( NULL != pointer ) pointer->Increment(); } void ByValue(MyClass object) { object.Increment(); } int main() { MyClass object; cout << "Original: "; object.Print(); cout << "ByRef: "; ByRef( object ); object.Print(); cout << "ByPointer: "; ByPointer( &object ); object.Print(); cout << "ByValue: "; ByValue( object ); object.Print(); return( 0 ); }
Why Cin and Cout cannot be used outside the main function?
You are completely wrong here.Another answer:There is nothing to say you cannot use cin or coutoutside the main() function (for example, you can use them in a function called from main()). However, using them before main() has been called (e.g. in the constructor of a static object) can have disastrous consequences: cin and cout are themselves static objects, and static initialisation order is undefined. Thus you could be calling them before they have been properly constructed.
What is namespace in c plus plus program?
A namespace is similar to a class in object oriented programming. A namespace contains functions defined by the programmer. for example namespace std contains functions like cout and cin.namespaces can be globaly declared like so: "using namespace std;"which includes all the functions located in the namespace std.if you only need to use cout you can globaly declare only cout like this "using std::cout;"orstd::cout
Syntex for accessing data members of the structure in c plus plus?
Use the member accessor (.) operator. struct object { int m_data; }; int main() { object o; o.m_data = 100; std::cout << o.m_data << std::cout; return(0); }
