Arrays&strings

                  Arrays 

It is a group of elements with same data type,used to allocate memory in sequential order 

Indexing : property of an array to distinguish all its stored data (because all elements have same name )  . " [ ] "  is called as SUBSCRIPT.

Eg.   arr[5]  ✒ arr[0], arr[1],arr[2],arr[3],arr[4].

Note : Array will always start with 0 index.

                             Array

              Static                    dynamic 

Static array : An array with fixed size  (can't be altered)

                        1. One dimensional

                        2.Two dimensional

                        3. Multi dimensional

Dynamic array: An array whose size can be changed at run time.

One dimensional : Array with single subscript  [ ]

Syntax 

    Data type arrayname [ size] = {value1,value2...n};

Eg ; 

       Int marks [6]={ 100,99,98,97,96,95};

Declaration&Initialisation : 

👉 Incase array is declared but not Intialised it           contains garbage values .

     Eg.  Int marks[6]  

                                Here array is intialised but not      declared so [0],[1]...[4] these values contain            grabage values (dummy values).

👉 Incase array is declared and intialised at least        one value rest will be zero.

       Eug. Int marks[6]={50};

                             [0]=50     rest [1] [2]......[5] will be zero.

👉We can skip index values when initilisation is done perfectly, compiler declares as Compile time.

         Eg: int marks[] = {50,40,30}

Run  time initilisation:

     int marks[3];

            scanf("%d%d%d",&marks[0],&marks[1],&marks[2]);

→In case there are more variables we cant write all so we use looping concept: 

      int marks[i];

         for(i=0;i<10;i++)

    {

        scanf("%d",&marks[i]);

     }

Example:

    Karthik wants to buy 10 items.He want to store the price of all items.Write a program to store 10

values.

Requirements:

1. Declaration of array size 10
2. scanf the prices
3. Display the prices

#include<stdio.h>

void main()

{

int i,item[10];

printf("enter the values");

for(i=0;i<10;i++)

{

    scanf("%d",&item[i]);

}

for(i=0;i<10;i++)

{

    printf("%d,item[%d]",i,item[i]);

}

}

Output:
item[0]=price

.....

....

....

item[9]=price

       

Two- Dimensional arrays:

          Used to represent a tabular data,[] [] rows and columns.

   →Total number of elements = rows*columns 

Syntax:

      Data type  Array name [R.size] [C.size]

     Eg: Matrix of 3*3

           A [3] [3]

Compile time initilisation:

      int A [3] [3]={{1,2,3},{4,5,6},{7,8,9}}

              

Run time initilization:

                    Scanf function is used in any program to initilisation at run time.(use as interative statements).

           

 Strings:

• It is a collection of characters.
• A string is called as an array of characters.
• A string must access by %s access specifier in C.
• A string always terminated with \0(Null) charatcers.
• A string always recognized in double quator.
• A string also consider space as character.

Example: Karthik-contain 7 character

Example: Karthik kamsala-contain 15 character.

Example:char ar[20] -contains 19 characters & 1 Null character

• All string functions are available in <string.h> header file.

String functions are:

•  strcat - concatenate two strings.
• strchr - string scanning operation.
• strcmp - compare two strings.
• strcpy - copy a string.
• strlen - get string length.
• strncat - concatenate one string with part of another.
• strncmp - compare parts of two strings.
• Note:
        strncmp(compares)
• →compares characters by charactor.
• →Gives result in 3 cases.
• Case 1: It first string > second ,result will be "True".
• Case 2: It first string < second ,result will be "False".
• Case 3:It first string = second , result will be "0".
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