Initialising a 2D array

Examples

•Assuming we have the following array b:

printf ("%d", b[0][0]);  /* prints 1 */

printf ("%d", b[1][0]);  /* prints 3 */

printf ("%d", b[1][1]);  /* prints 4 */

Single vs multidimensional

Dimensionality

—Determined by the number of subscripts of an array.

•x[i]  

•y[i][j]

•z[i][j][k] 

Some more tips..

Single Integer

Another array example

//Find the lowest number in the array num[10]

main()

{

int num[10]={4,9,11,2,13,77,8,19,21,1};

int min, i;

min = num[0];

for (i=1; i<10; i++) {

  if (num[i] < min)

     min = num[i];

}

printf(“The minimum is %d”, min);

}

—

—Array example

—

/* which type of integer is valid in array declaration*/

#include <stdio.h>

int main(void)

  {

  int x[5];  /* x[5] is array initialization /

  x[0]=23;  /* valid */

  x[2.3]=5;  /* invalid: index is not an int */

  return 0;

  }

Examples

int x [5] = { 1,2,3,4,5 };  size 10 bytes

—creates array with elements 0-4 values 1-5

int x [5] = {4,3};  size 10 bytes

—creates array with elements 0-4 values 4,3,0,0,0

int x [ ] = {1,2,3};  size 6 bytes

—creates array with elements 0-2 values 1,2,3

char c[4] = {‘M’, ‘o’ , ‘o’ };  size 4 bytes

—creates array with elements 0-3 values M o o NULL

1-D Array Declaration

—To declare a 1-D Array, we specify 1 size 

  data_type array_name [size];

—For Eg.

     int number[30];

     float marks[60];

     char name[15];

Difference Between Ordinary Variable & Arrays

—Ordinary variable store one value at a time

—Arrays are used for storing more than one value at a time in a single variable name

Arrays

What is an array?

—An array is a consecutive series of variables that share one variable name

——The individual data items in an array must all be of the same data type, accessed using an index

——Often used when dealing with multiple data items possessing common characteristics

——Ex. 24 hourly temperature readings might be stored in array named temperature