C++ Programming Code Examples
C++ > Beginners Lab Assignments Code Examples
Implimentation of a list using a linked list with pointers
/* Implimentation of a list using a linked list with pointers */
#include <iostream.h>
struct element {
int number;
element *next;
};
/* the operators declared on the type list.*/
void read(element *&list);
void write(element *list);
int length(element *list);
int position(element *list, int num);
void remove(element *&list,int position);
void insert(element *&list,int new_num,int position);
element *ele(element *list,int position);
void add(int new_num,element *&list,element *this_el);
void main()
{
element *list,*p,*q;
int leng;
read(list);
write(list);
q = ele (list,3);
add (5,list,q);
write(list);
insert(list,10,2);
write(list);
remove(list,4);
write(list);
insert(list,12,1);
write(list);
leng = position(list,10);
cout<< " pos of 10 is " << leng <<endl;
cout<< " The length of the list is: " << length(list)<<endl;
cout<<endl;
]
}
/* reading a list from input */
void read(element *&list)
{
element *p,*last;
list = new element;
p = list;
cout<< " enter a number";
cin>>p->number;
while (!cin.eof())
{
p->next = new element;
last = p;
p = p->next;
cout<< " enter a number ";
cin>>p->number;
}
delete (p);
last->next = NULL;
}
/* writing a list on the output */
void write(element *list)
{
element *p;
cout<<endl;
p = list;
while (p!=NULL)
{
cout<< p->number<<" ";
p=p->next;
}
cout<<endl;
}
/* Gets a list and returns its length */
int length (element *list)
{
element *p;
int count=0;
p=list;
while (p!=NULL)
{
count++;
p = p->next;
}
return count;
}
/*Gets an element and returns its positon in the list. If the element*/
/*is not in the list, returns 0 */
int position(element *list,int num)
{
element *p;
int i=1;
for (p=list;p!=NULL;p=p->next)
{
if ((p->number)==num)
return i;
i++;
}
return 0;
}
/*Gets a number and removes the element that stays in this position */
void remove(element *&list,int position)
{
element *before,*p;
if (position==1)
{
before=list;
list = list->next;
delete (before);
}
else
{
before = ele (list,position-1);
if (before!=NULL)
{
p = before->next;
before->next = p->next;
delete (p);
}
}
}
/* Insert a new element to be the i-th element of the list */
/* the function uses the function add*/
void insert(element *&list,int new_num,int position)
{
element *p;
if (position==1)
add(new_num,list,NULL);
else
{
p = ele(list,position-1);
add(new_num,list,p);
}
}
/* Gets a position in the list and returns a pointer to the element*/
/* in this position*/
element *ele(element *list,int position)
{
element *p=list;
int i;
for (i=1;i<position;i++)
{
if (p==NULL)
return p;
p=p->next;
}
return p;
}
/* Add a new element after a given element.If the given element is NULL*/
/* Add the new element to be the first element*/
void add(int new_num,element *&list,element *this_el)
{
element *p;
if (list==NULL)
{
list = new element;
list->number = new_num;
list->next = NULL;
}
else
{
p = new element;
p->number = new_num;
if (this_el==NULL)
{
p->next = list;
list = p;
}
else
{
p->next=this_el->next;
this_el->next = p;
}
}
}
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.
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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.
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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).
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.
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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.
A predefined object of the class called iostream class is used to insert the new line characters while flushing the stream is called endl in C++. This endl is similar to \n which performs the functionality of inserting new line characters but it does not flush the stream whereas endl does the job of inserting the new line characters while flushing the stream. Hence the statement cout<<endl; will be equal to the statement cout<< '\n' << flush; meaning the new line character used along with flush explicitly becomes equivalent to the endl statement in C++.
Write block of data. Inserts the first n characters of the array pointed by s into the stream. This function simply copies a block of data, without checking its contents: The array may contain null characters, which are also copied without stopping the copying process. Internally, the function accesses the output sequence by first constructing a sentry object. Then (if good), it inserts character into its associated stream buffer object as if calling its member function sputc until n characters have been written or until an insertion fails (in this case it sets the badbit flag). Finally, it destroys the sentry object before returning.
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.
Read block of data. Extracts n characters from the stream and stores them in the array pointed to by s. This function simply copies a block of data, without checking its contents nor appending a null character at the end. If the input sequence runs out of characters to extract (i.e., the end-of-file is reached) before n characters have been successfully read, the array pointed to by s contains all the characters read until that point, and both the eofbit and failbit flags are set for the stream. Internally, the function accesses the input sequence by first constructing a sentry object (with noskipws set to true). Then (if good), it extracts characters from its associated stream buffer object as if calling its member functions sbumpc or sgetc, and finally destroys the sentry object before returning.
Deallocate storage space. Default deallocation functions (single-object form). A delete operator is used to deallocate memory space that is dynamically created using the new operator, calloc and malloc() function, etc., at the run time of a program in C++ language. In other words, a delete operator is used to release array and non-array (pointer) objects from the heap, which the new operator dynamically allocates to put variables on heap memory. We can use either the delete operator or delete [ ] operator in our program to delete the deallocated space. A delete operator has a void return type, and hence, it does not return a value.
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.
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