Kamis, 12 Desember 2013

How to Store Multiple values in Computer Programming: Array

One data item can only be stored in one variable, in the context of computer programming. If programmer want to store more information in the memory, he/she should have more variables. Programmer can choose another option that is an Array.

Suppose that a student has scored 90 marks. These marks can be stored in a variable in c programming language as shown below:
int marks=90;

After executing this statement, the value 90 will be stored in the variable marks. Suppose there programmer needs to store marks of 10 students. In such case, we have to use 10 variables like marks1, marks2, marks3, …, marks10. But, if it is required to store the marks of 100 students, definitely it is not feasible to use 100 variables marks1, marks2, marks3, …, marks100. In mathematics, we use sets to group the items of similar kind. For example, consider the set shown below:

Marks = {75, 76, 78, 79, 86, 56, 98, 89, 56, 89}

This is a set of 10 students. Note that every item can be accessed by prefixing marks along with the position of marks in the sheet. The first item 75 corresponds to the marks of first student, 76 corresponds to the marks of second student and so on i.e., marks1=75, marks2=76, marks3=78, ….., marks10=89. In C language, this is where; the concept of arrays is used. Since all the marks are of the same type, we can group and refer all the marks with a common name using arrays.

An array is defined as an ordered set of similar data items. All the data items of an array are stored in consecutive memory locations in main memory. The elements of an array are of same data type and each item can be accessed using the same name. e.g., consider an array of marks of 5 students as shown below:

How to Store Multiple values in Computer Programming: Array

To refer an item in the array, we specify the name of the array along with position of the item. The position of the item must be written within square brackets '[ ]'. The position of the item enclosed within square brackets is called 'subscript' or 'index'. For example, the above figure represents an integer array called marks where marks of 5 students are stored. The marks of each student can be accessed as shown below:

  • Marks[0] i.e. 75 – represents marks of first student
  • Marks[0] i.e. 76 – represents marks of second student
  • Marks[0] i.e. 78 – represents marks of third student
  • Marks[0] i.e. 79 – represents marks of fourth student
  • Marks[0] i.e. 86 – represents marks of fifth student

Note: Using Marks[0] through Marks[n-1] we can access the marks of n students in general.

In an array it is not possible to have a group of items with different data types. For example,

How to Store Multiple values in Computer Programming: Array

This is an invalid way of storing the elements in an array. This is because, it is a collection of multiple datatypes, so we have to classify the array. The classification will be done in next article.

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