10. 1 Declaration of an Array : To declare an array in C, it is necessary to specify the type of the element and the number of elements required by an array as follows: Type array name [ array size ]



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Arrays in C :

Overview :


In C programming, one of the frequently arising problem is to handle similar types of data. C programming language provides a data structure called the array, which can store a fixed-size sequential collection of elements of the same type. An array is used to store a collection of data, but it is often more useful to think of an array as a collection of variables of the same type. All arrays consist of contiguous memory locations. The lowest address corresponds to the first element and the highest address to the last element.

Description :


Arrays in C act to store related data under a single variable name with an index, also known as a subscript. It is easiest to think of an array as simply a list or ordered grouping for variables of the same type. As such, arrays often help a programmer organize collections of data efficiently and intuitively.
Arrays are of two types:


  1. One-dimensional arrays

  2. Multidimensional arrays


10.1 Declaration of an Array :
To declare an array in C, it is necessary to specify the type of the element and the number of elements required by an array as follows:
Type array_name [ array_size ];

This is called a single-dimensional or one dimensional array. The array_size must be an integer constant greater than zero and type can be any valid C data type. For example, to declare a 10-element array called Name of type char, use this statement:


char Name[10];
Now the character array is sufficient to hold upto 10 characters or integers. An element is accessed by indexing the array name. This is done by placing the index of the element within square brackets after the name of the array.

10.2 Initializing an Array :
Array initialization can be done in one of the following ways :
1) The number of values between braces { } cannot be greater than the number of elements that is declared for the array between square brackets [ ] i.e the size of the array.
E.g : int Array[5] = {1,2,5,10,-3};
Consider the given program to initialize an array :
#include "stdafx.h"
int _tmain(int argc, _TCHAR* argv[])

{

int array[5] = { 1, 3, -2, 35, 100};
return 0;

}

The above program shows another method to initialize the elements in an array. Here, the elements of array are initialized during the declaration process by placing values between curly braces and separating them using commas.

2) If the size of the array is omitted, an array just big enough to hold the initialization is created. Therefore, if the user writes:
E.g : int Array[] = {1,2,5,10,-3};
An array similar to the one mentioned above is created with the declared elements. This is very useful in that the size of the array can be controlled by simply adding or removing initialized elements from the definition without the need to adjust the dimension. If the dimension is specified, but not all elements in the array are initialized, the remaining elements will contain a value of 0. This is very useful, especially when we have very large arrays.
3) It is also possible to assign a value to a single element of the array by specifying the array index.

E.g : Array[3]=100;
Array[0]=10;
Consider the given example :
int _tmain(int argc, _TCHAR* argv[])

{

int array[5];

array[0] = 10;

array[1] = 20;

array[2] = 30;

array[3] = 40;

array[4] = 50;
return 0;

}
The above program shows one method to initialize the elements in an array. Here, the elements of array are individually initialized with values by specifying the array index as given above.
Consider the given example to sort an array of elements :
3.png

Figure 10.1
The above figure 10.3 shows an example to sort an array of 5 elements using the bubble sort technique. The program shows the transition of the first iteration in the watch window. Since the first element of the array is greater than the second element, we use a temporary variable to swap the two values.

5.png

Figure 10.2

The above figure 10.4 shows an example to sort an array of 5 elements using the bubble sort technique. The program shows the output of the first iteration of the sorting process in the watch window. The first and the second values of the array have been swapped and the second iteration is started which checks the next two elements in the array. In this way, all the elements in the array are sorted in the required ascending order.










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