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String Literals and Constants in C Language

There is no separate data type for strings in C language. In C language, a string is an array of characters and terminated by NULL character which is denoted by the escape sequence '0'. A NULL terminated string is the only type string defined using C language.

A string is stored as a sequence of characters in an array terminated by \0. For example, consider the string "DOTPROGRAMMING". This string is stored in the form of an array as shown below:

String Literals and Constants in Computer Programming: C Language
Note that the characters are stored from location zero. Each location holds one character string from 0 to 14. The string always ends with NULL. Character denoted by '\0'. Here, the string "DOTPROGRAMING" is called a string literal.

String Literal or Constant

A string literal or constant is a sequence of characters enclosed within double quotes. For example, "DOT PROGRAMMING", "DOT", "PROGRAMMING" are all string literals. When a string literal is defined, the C compiler does the following activities:

  • The compiler creates an array of characters.
  • Initializes each location of array with the characters specified within double quotes in sequence.
  • Null-terminates the string that is appends ‘\0’ at the end of the string. This is done by the compiler automatically.
  • Stores the starting address of the string constant that can be used later. For example, the literals "DOT", and "PROGRAM" can be stored in the memory as shown below:

String Literals and Constants in Computer Programming: C Language

Referencing String Literal or Constant

An array of integers is stored in contiguous memory locations, it is clear from the above figures that a string literal is also stored in memory contiguously one after the other. So, each character of the literal or constant can be accessed using index (array or pointer concept can be used). For example, consider the following program:

main()
{
clrscr();
printf("5c","DOT"[0]);
printf("5c","DOT"[1]);
printf("5c","DOT"[2]);
getch();
 }

The entire string can be referred and display as shown below:

main()
{
clrscr();
printf("DOT");
getch();
 }

Each of the above program will outputs "DOT" string on the monitor or any output device connected with the PC.

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Binary Search Linear Search Works only on sorted items. such as  1,2,3,4,5,6  etc
Works on sorted as well as unsorted items. 12,4,5,3,2,1 etc Very efficient if the items are sorted Very efficient if the items are less and present in the beginning of the list. such as Suppose your list items are : 12,3,4,5,1 and you want to search 12 number then you get beginning in the list. Works well with arrays and not on linked lists. Works with arrays and linked lists.
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Memory representation of Linked List Data Structures in C Language

Memory representation of Linked List

             In memory the linked list is stored in scattered cells (locations).The memory for each node is allocated dynamically means as and when required. So the Linked List can increase as per the user wish and the size is not fixed, it can vary.

               Suppose first node of linked list is allocated with an address 1008. Its graphical representation looks like the figure shown below:


      Suppose next node is allocated at an address 506, so the list becomes,



  Suppose next node is allocated with an address with an address 10,s the list become,


The other way to represent the linked list is as shown below:




 In the above representation the data stored in the linked list is “INDIA”, the information part of each node contains one character. The external pointer root points to first node’s address 1005. The link part of the node containing information I contains 1007, the address of next node. The last node …