C++ Programming Code Examples
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String Char Indexing
/* String Char Indexing */
#include <string>
#include <iostream>
using namespace std;
int main()
{
string str( "hello" );
char ch = str[0];
str[0] = 'j';
ch = str. at( 0 );
str.at(0) = 'h';
ch = str[ 1000 ];
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.
#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.
Get character in string. Returns a reference to the character at position pos in the string. This function is used for accessing individual characters. The function automatically checks whether pos is the valid position of a character in the string (i.e., whether pos is less than the string length), throwing an out_of_range exception if it is not. The first character in a string is denoted by a value of 0 (not 1).
A return statement ends the processing of the current function and returns control to the caller of the function. A value-returning function should include a return statement, containing an expression. If an expression is not given on a return statement in a function declared with a non-void return type, the compiler issues an error message. If the data type of the expression is different from the function return type, conversion of the return value takes place as if the value of the expression were assigned to an object with the same function return type.
As the name already suggests, these operators help in assigning values to variables. These operators help us in allocating a particular value to the operands. The main simple assignment operator is '='. We have to be sure that both the left and right sides of the operator must have the same data type. We have different levels of operators. Assignment operators are used to assign the value, variable and function to another variable. Assignment operators in C are some of the C Programming Operator, which are useful to assign the values to the declared variables. Let's discuss the various types of the assignment operators such as =, +=, -=, /=, *= and %=. The following table lists the assignment operators supported by the C language:
The stringstream, ostringstream, and istringstream objects are used for input and output to a string. They behave in a manner similar to fstream, ofstream and ifstream objects. The function str() can be used in two ways. First, it can be used to get a copy of the string that is being manipulated by the current stream string. This is most useful with output strings. The first form (1) returns a string object with a copy of the current contents of the stream. The second form (2) sets s as the contents of the stream, discarding any previous contents. The object preserves its open mode: if this includes ios_base::ate, the writing position is moved to the end of the new sequence. Internally, the function calls the str member of its internal string buffer object.
Strings are objects that represent sequences of characters. The standard string class provides support for such objects with an interface similar to that of a standard container of bytes, but adding features specifically designed to operate with strings of single-byte characters. The string class is an instantiation of the basic_string class template that uses char (i.e., bytes) as its character type, with its default char_traits and allocator types. Note that this class handles bytes independently of the encoding used: If used to handle sequences of multi-byte or variable-length characters (such as UTF-8), all members of this class (such as length or size), as well as its iterators, will still operate in terms of bytes (not actual encoded characters).
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.
An array is defined as the collection of similar type of data items stored at contiguous memory locations. Arrays are the derived data type in C++ programming language which can store the primitive type of data such as int, char, double, float, etc. It also has the capability to store the collection of derived data types, such as pointers, structure, etc. The array is the simplest data structure where each data element can be randomly accessed by using its index number. C++ array is beneficial if you have to store similar elements. For example, if we want to store the marks of a student in 6 subjects, then we don't need to define different variables for the marks in the different subject. Instead of that, we can define an array which can store the marks in each subject at the contiguous memory locations.
To reverse a number in C++, then you have to ask to the user to enter a number. Now, start reversing that number to find its reverse and then display its reverse on the screen. Make a
Quick sort is based on an 'algorithmic' design pattern called 'divide-conquer'. Unlike Merge Sort it does not require 'extra memory space'. The average time complexity is "O(n*log(n))"
To declare such a function, precede its name with * and &. In the body of the function, you can do whatever is appropriate. An important rule with this type of "function" is that it must
