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C++ Programming Code Examples

C++ > For Loops and While Loops Code Examples

Exception in for_each in C++ programming

/* Exception in for_each in C++ programming If the function throws an exception then for_each will also throw the same exception and will break/terminate the loop. Below is an example for the exception case. */ #include #include using namespace std; void fun1(int x) { cout << x << " "; if (x % 2 == 0) { throw 100; } } struct Class1 // object type function { void operator() (int x) { cout << x << " "; if (x % 2 == 0) { throw 100; } } } myobject; int main() { vector v1; v1.push_back(11); v1.push_back(23); v1.push_back(4); v1.push_back(13); try { for_each(v1.begin(), v1.end(), fun1); } catch (int i) { cout << endl << "Got exception...Value thrown is " << i << endl; } try { for_each (v1.begin(), v1.end(), myobject); } catch (int i) { cout << endl << "Got exception...Value thrown is " << i << endl; } return 0; }

Consider a situation, when we have two persons with the same name, jhon, in the same class. Whenever we need to differentiate them definitely we would have to use some additional information along with their name, like either the area, if they live in different area or their mother's or father's name, etc. Same situation can arise in your C++ applications. For example, you might be writing some code that has a function called xyz() and there is another library available which is also having same function xyz(). Now the compiler has no way of knowing which version of xyz() function you are referring to within your code.

n C++, we can change the way operators work for user-defined types like objects and structures. This is known as operator overloading. Suppose we have created three objects c1, c2 and result from a class named Complex that represents complex numbers. Since operator overloading allows us to change how operators work, we can redefine how the + operator works and use it to add the complex numbers of c1 and c2 by writing the following code:

Return iterator to beginning. Returns an iterator pointing to the first element in the vector. Notice that, unlike member vector::front, which returns a reference to the first element, this function returns a random access iterator pointing to it. If the container is empty, the returned iterator value shall not be dereferenced. The C++ function std::vector::begin() returns a random access iterator pointing to the first element of the vector. This function does not accept any parameter.

A relational operator is used to check the relationship between two operands. C++ Relational Operators are used to relate or compare given operands. Relational operations are like checking if two operands are equal or not equal, greater or lesser, etc. Relational Operators are also called Comparison Operators.

A program shall contain a global function named main, which is the designated start of the program in hosted environment. main() function is the entry point of any C++ program. It is the point at which execution of program is started. When a C++ program is executed, the execution control goes directly to the main() function. Every C++ program have a main() function.

Add element at the end. Adds a new element at the end of the vector, after its current last element. The content of val is copied (or moved) to the new element. This effectively increases the container size by one, which causes an automatic reallocation of the allocated storage space if -and only if- the new vector size surpasses the current vector capacity. push_back() function is used to push elements into a vector from the back. The new value is inserted into the vector at the end, after the current last element and the container size is increased by 1. This function does not return any value.

In C++, vectors are used to store elements of similar data types. However, unlike arrays, the size of a vector can grow dynamically. That is, we can change the size of the vector during the execution of a program as per our requirements. Vectors are part of the C++ Standard Template Library. To use vectors, we need to include the vector header file in our program. The vector class provides various methods to perform different operations on vectors. Add Elements to a Vector: To add a single element into a vector, we use the push_back() function. It inserts an element into the end of the vector. Access Elements of a Vector: In C++, we use the index number to access the vector elements. Here, we use the at() function to access the element from the specified index.

When executing C++ code, different errors can occur: coding errors made by the programmer, errors due to wrong input, or other unforeseeable things. When an error occurs, C++ will normally stop and generate an error message. The technical term for this is: C++ will throw an exception (throw an error). An exception is a problem that arises during the execution of a program. A C++ exception is a response to an exceptional circumstance that arises while a program is running, such as an attempt to divide by zero. Exceptions provide a way to transfer control from one part of a program to another. C++ exception handling is built upon three keywords: try, catch, and throw. The try and catch keywords come in pairs:

In computer programming, loops are used to repeat a block of code. For example, when you are displaying number from 1 to 100 you may want set the value of a variable to 1 and display it 100 times, increasing its value by 1 on each loop iteration. When you know exactly how many times you want to loop through a block of code, use the for loop instead of a while loop. A for loop is a repetition control structure that allows you to efficiently write a loop that needs to execute a specific number of times.

In computer programming, we use the if statement to run a block code only when a certain condition is met. An if statement can be followed by an optional else statement, which executes when the boolean expression is false. There are three forms of if...else statements in C++: • if statement, • if...else statement, • if...else if...else statement, The if statement evaluates the condition inside the parentheses ( ). If the condition evaluates to true, the code inside the body of if is executed. If the condition evaluates to false, the code inside the body of if is skipped.

Return iterator to end. Returns an iterator referring to the past-the-end element in the vector container. The past-the-end element is the theoretical element that would follow the last element in the vector. It does not point to any element, and thus shall not be dereferenced. Because the ranges used by functions of the standard library do not include the element pointed by their closing iterator, this function is often used in combination with vector::begin to specify a range including all the elements in the container. If the container is empty, this function returns the same as vector::begin. This function does not accept any parameter.

In C++, classes and structs are blueprints that are used to create the instance of a class. Structs are used for lightweight objects such as Rectangle, color, Point, etc. Unlike class, structs in C++ are value type than reference type. It is useful if you have data that is not intended to be modified after creation of struct. C++ Structure is a collection of different data types. It is similar to the class that holds different types of data. A structure is declared by preceding the struct keyword followed by the identifier(structure name). Inside the curly braces, we can declare the member variables of different types.

#include is a way of including a standard or user-defined file in the program and is mostly written at the beginning of any C/C++ program. This directive is read by the preprocessor and orders it to insert the content of a user-defined or system header file into the following program. These files are mainly imported from an outside source into the current program. The process of importing such files that might be system-defined or user-defined is known as File Inclusion. This type of preprocessor directive tells the compiler to include a file in the source code program.

Apply function to range. Applies function fn to each of the elements in the range [first,last). C++ algorithm::for_each function is used to apply the specified function fn to each element in the range [first, last). for_each loop applies a function to the range of elements of a collection. In other words each element from the collection will be passed to the function as a parameter and function will be executed the number of times elements present in a collection. This loop is defined in a algorithm header so have to include this header in your program to use for_each

In while loop, condition is evaluated first and if it returns true then the statements inside while loop execute, this happens repeatedly until the condition returns false. When condition returns false, the control comes out of loop and jumps to the next statement in the program after while loop. The important point to note when using while loop is that we need to use increment or decrement statement inside while loop so that the loop variable gets changed on each iteration, and at some point condition returns false. This way we can end the execution of while loop otherwise the loop would execute indefinitely. A while loop that never stops is said to be the infinite while loop, when we give the condition in such a way so that it never returns false, then the loops becomes infinite and repeats itself indefinitely.




In the C++ Programming, The static keyword allows a variable to maintain its value among different function calls. If the value of a static variable changes when the variable has been






Using Fibonacci numbers we calculate mid of data array to search the data item. 'Calculate' the mid of the array. Divide the array into two subarray. 'Compare the item' by mid element

This algorithm generates a undirected graph for the given "Degree Sequence". It does not include self-edge and multiple edges. So this algorithm 'takes the input' of the number of

Prints a total number of combination possible for given n and r value. The "time complexity" of this algorithm is O(n). This algorithm takes the input of n and r value. Function to find the