C++ Programming Code Examples
C++ > Code Snippets Code Examples
Wrap char pointer to a String class
/* Wrap char pointer to a String class */
#include <iostream>
#include <cstring>
#include <cstdlib>
using namespace std;
class StringClass {
char *p;
int len;
public:
StringClass();
StringClass(char *s, int l);
char *getstring() {
return p;
}
int getlength() {
return len;
}
};
StringClass::StringClass()
{
p = new char [255];
if(!p) {
cout << "Allocation error\n";
exit(1);
}
*p = '\0'; // null string
len = 255;
}
StringClass::StringClass(char *s, int l)
{
if(strlen(s) >= l) {
cout << "Allocating too little memory!\n";
exit(1);
}
p = new char [l];
if(!p) {
cout << "Allocation error\n";
exit(1);
}
strcpy(p, s);
len = l;
}
int main()
{
StringClass stringObject1;
StringClass stringObject2("Hello World", 100);
cout << "stringObject1: " << stringObject1.getstring() << " - Length: ";
cout << stringObject1.getlength() << '\n';
cout << "stringObject2: " << stringObject2.getstring() << " - Length: ";
cout << stringObject2.getlength() << '\n';
return 0;
}
Allocate storage space. Default allocation functions (single-object form). A new operator is used to create the object while a delete operator is used to delete the object. When the object is created by using the new operator, then the object will exist until we explicitly use the delete operator to delete the object. Therefore, we can say that the lifetime of the object is not related to the block structure of the program.
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.
#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.
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.
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).
Return length of string. Returns the length of the string, in terms of bytes. This function is used to find the length of the string in terms of bytes. This is the actual number of bytes that conform the contents of the string , which is not necessarily equal to the storage capacity. This is the number of actual bytes that conform the contents of the string, which is not necessarily equal to its storage capacity. Note that string objects handle bytes without knowledge of the encoding that may eventually be used to encode the characters it contains. Therefore, the value returned may not correspond to the actual number of encoded characters in sequences of multi-byte or variable-length characters (such as UTF-8).
The main purpose of C++ programming is to add object orientation to the C programming language and classes are the central feature of C++ that supports object-oriented programming and are often called user-defined types. A class is used to specify the form of an object and it combines data representation and methods for manipulating that data into one neat package. The data and functions within a class are called members of the class.
In C++, constructor is a special method which is invoked automatically at the time of object creation. It is used to initialize the data members of new object generally. The constructor in C++ has the same name as class or structure. Constructors are special class functions which performs initialization of every object. The Compiler calls the Constructor whenever an object is created. Constructors initialize values to object members after storage is allocated to the object. Whereas, Destructor on the other hand is used to destroy the class object. • Default Constructor: A constructor which has no argument is known as default constructor. It is invoked at the time of creating object.
The exit function terminates the program normally. Automatic objects are not destroyed, but static objects are. Then, all functions registered with atexit are called in the opposite order of registration. The code is returned to the operating system. An exit code of 0 or EXIT_SUCCESS means successful completion. If code is EXIT_FAILURE, an indication of program failure is returned to the operating system. Other values of code are implementation-defined. Calls all functions registered with the atexit() function, and destroys C++ objects with static storage duration, all in last-in-first-out (LIFO) order. C++ objects with static storage duration are destroyed in the reverse order of the completion of their constructor. (Automatic objects are not destroyed as a result of calling exit().)
The pointer in C++ language is a variable, it is also known as locator or indicator that points to an address of a value. In C++, a pointer refers to a variable that holds the address of another variable. Like regular variables, pointers have a data type. For example, a pointer of type integer can hold the address of a variable of type integer. A pointer of character type can hold the address of a variable of character type. You should see a pointer as a symbolic representation of a memory address. With pointers, programs can simulate call-by-reference. They can also create and manipulate dynamic data structures. In C++, a pointer variable refers to a variable pointing to a specific address in a memory pointed by another variable.
Get string length. Returns the length of the C string str. C++ strlen() is an inbuilt function that is used to calculate the length of the string. It is a beneficial method to find the length of the string. The strlen() function is defined under the string.h header file. The strlen() takes a null-terminated byte string str as its argument and returns its length. The length does not include a null character. If there is no null character in the string, the behavior of the function is undefined.
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.
Copy string. Copies the C string pointed by source into the array pointed by destination, including the terminating null character (and stopping at that point). To avoid overflows, the size of the array pointed by destination shall be long enough to contain the same C string as source (including the terminating null character), and should not overlap in memory with source. strcpy() is a standard library function in C/C++ and is used to copy one string to another. In C it is present in string.h header file and in C++ it is present in cstring header file. It copies the whole string to the destination string. It replaces the whole string instead of appending it. It won't change the source string.
To concatenate strings in 'C++' Programming, you have to ask to enter the 2 string and start concatenating one string into other using the strcat() function as shown here in the sample
Algorithm takes the input of "n" data element and 'prints all possible combination'. Function to 'Print array element' according to the code in the 'Argument List'. For that, it generates n
In C++ programming, you can create nested 'namespaces'. One namespace can be a part of another namespace. Simply we can create namespace X, which will contain namespace
To get the IP address of your computer in c++ programming, use the function system() and place the command 'ipconfig' after providing the full path of 'System32' i.e., C:\\Windows\\
