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/*C01 - Array Introduction */
/*Array Basic:
c_01- array introduction
1. a company has 1000 employees, then we need
1000 variables
it take time
become heavy
consume space
2. Array can store 1000 value in one variables
normally = emp_id1, emp_id2, emp_id3...emp_idn , ( access by variable names)
array = int emp_id = new int[999] (access by index)
3. new int[999] = create an array of 1000 blockand store value in it
4. array is an object in java / super class- object / heap memory allocation /
5. advantages = save multiple valus same time / array fast / save array of obects also
6. disadvantages = fixed size/ wastage of memory/ similar data type / traverse
/* C_02, Array Type, D, C, I, DC, DCI */
// array type
1. single dimensions - (1dA) - [ single row / coloumn]
2. multi dimensions - (2d, 3d) -[ multiple row/ column]
// Declare -
int[] a; /* a is one dimension int type (primitive/ class) array */
// Creation - size or lenght , new- dyanmic memory allocation
a = new int[3]; /* size provide is compulsory */
// Declare + Creation in one line
int[] a = new int[3];
// Initilization /* putting value */
int[] a;
a = new int[3];
a[0] = 10;
a[1] = 20;
a[2] = 30;
// DCI in one line - static memory allocation,w/o using new
int[] a = {10,20,30};
int[] a = new int[]{10,20,30};
/* C_03, for interview */
int[] a; /* right */
int a[]; /* right */
int []a; /* right */
int[]a; /* right */
int[3] a; /* wrong */
int a [3] /* wrong */
int[] a,b; /* both array */
int []a,b; /* both array */
int a[],b; /* a array , b not */
int [] a = new int [0]; /* compile and run */
int [] a = new int[-3]; /* compile but not run, negative array size exception */
int []a = new int[3];
a[3] = 40; /* error , array index out of bound */
/* C_09, 2d Matrix array , array of array, D, C, I, DC, DCI */
Declare
int[][] a; /* a is a two dimensional int type array */
// for the sake on understanding , row and column
Creation
int [][]a;
a = new int[2][3]; /* 2 row 3 column ( array conatain two row, and the both row contain 3 element of array) */
array of array
[] []
[][][] [][][]
Initilization
int[][] a;
a=new int[2][3];
a[0][0] = 10; a[0][1] = 20; a[0][2] = 30;
a[1][0] = 40; a[1][1] = 50; a[1][2] = 60;
Declare + Creation
int[][]a=new int[2][3]; /* single line*/
Declare + Creation + Initilization
int[][]a=new int{ {10,20,30} , {40,50,60} };
C_09Home PREVIOUS NEXT
/* C_10 - interview questions */
interview
int[] []a;
int a[][];
int[] a[];
int[][] a,b; /* both 2d array */
int[] a[],b;/* a=2dA, b=1dA */
int[]a[],b[]; /* both2dA */
int[][]a,b[]; /* a=2dA, b=3dA */
int[][]a,[]b; /* a=2dA, b= compile time error*/
/* C_11 : 2d Jagged array */
Declare
int[][] a;
Create
a=new int[2][]; // only row no column
a[0] = new int[4]; // first row contain 4 element of array
a[1] = new int[3]; // second row contain 3 element of array
Initilization
a[0][0]=10; a[1][0]=50;
a[0][1]=20; a[1][1]=60;
a[0][2]=30; a[1][2]=70;
a[0][3]=40;
Declare + Creation
int[][]a= new int[2][];
a[0] = new int[4];
a[1] = new int[3];
Declare + Creation + Initilization
int[][]a = { {10,20,30,40} , {50,60,70} }
/* C_12 - interview questions */
interview
int[][]a={ [10,20,30,40] , {50,60} , {70,80,90} }
sop (a); /* [[I@ 2d array class */
sop(a[0]); /* [I@ */
sop(a[0][0]);/* 10 */
sop(a.lenght);/* 3 */
sop(a[0].lenght); /* 4 */
sop(a[0][0].lenght); /*error */
int[][]a = new int[2][];
sop(a); /* [[I@ */
sop(a[0]); /* null */
sop(a[0][0]);/* run time exception */
sop(a.lenght);/* 2 */
sop(a[0].lenght); /* error */
/* C_19 : 3d array, array of array of array */
Declare
int[][][] a;
Creation
a = new int[2][][];
a[0] = new int[2][ ]; /* contain 2 row */
a[0][0] = new int[3]; /* the above further contain array of 3 element */
a[0][1] = new int[2];
a[1] = new int[2][ ];
a[1][0] = new int[2];
a[1][1] = new int[3];
Declare + Creation
int [][][]a=new int [2][3][2];
Initilization
a[0][0][0] = 10; a[1][0][0] = 10;
a[0][0][1] = 10; a[1][0][1] = 10;
a[0][1][0] = 10; a[1][1][0] = 10;
a[0][1][1] = 10; a[1][1][1] = 10;
a[0][2][0] = 10; a[1][2][0] = 10;
a[0][2][1] = 10; a[1][2][1] = 10;
Declare + creation + Initilization
int[][][] a = {{ {10,20} ,{30,40,50,60}, {70,80,90} }}
exp.2
int[][][] c = new int[2][3][2];
DCI in one line for above example.
int[][][] c = {{{1,2}}}; // two block. let say value = 1 and 2
int[][][] c = {{{4,5,6},{7,8,9}}}; // both locaction contin 3 more blocks, put an array instead of 1;
int[][][] c = { { {10,11},{12,13},{14,15} }, { {10,11},{12,13},{14,15} } }; // both block contin 2 block array, which
/* C_20, 3dA interview */
int [] [][]a; /* all right */
int [][]a[]; /* all right */
int []a[][]; /* all right */
a[0][0] = 10;/* wrong*/
sop(a); /* [[[I@ */
sop(a[0]); /* [[I@ */
sop(a[0][0]); /* [I@ */
sop(a[0][0][0]);/* 10 */
sop(a.length); /* 1*/
sop(a[0].length)/* 3*/
sop(a[0][0].length) /* 2*/
sop(a[0][1]).lenght = /* 4 */
