Interview
data structure
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Interview study book Cambridge IGCSE and O Level Computer Science Second Edition of David Watson, Helen Williams (data structure) - ISBN: 9781398320758 (n)
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Class notes Computing Cambridge IGCSE/GCSE Computer Science
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Computer Science notes
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Cambridge Computer Science IGCSE and O level notes
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Understanding Memory and Arrays in ProgrammingIn programming, memory is essentially a long tape of bytes, with each byte containing 8 bits. This can be
extended to both sides, making it open-ended. To understand the need for arrays, we need to examine
how areas can be declared, initialized, and represented in memory.
Storing Values in Memory
To store a value in memory, we need to know how much space will be allocated for it. For example, the
data type int typically takes up 4 bytes to store an integer. The number 5 would need to be converted to
binary, which is 32 bits or 4 bytes. In traditional compilers, we generally take 2 or 4 bytes to be the data
type for storing numbers. So, if we were storing an integer, it would take up 2-4 bytes in memory.
The memory manager would allocate some memory for storing a variable, and the value stored in
memory would be represented in binary. For example, the value stored in a variable could be 5, which
would be represented as 101 in binary.
Using Arrays
An array is a collection of more than one element of the same datatype. For example, an array of
characters would be of the data type char, and an array of integers would be of the data type int. The
number of elements in an array is determined by the size of the array.
To declare an array in programming, we use a specific syntax. In C language, for example, we would
write:
int n;
to declare an integer variable. To declare an array, we would use:
int a[16];
This creates an array called "a" with 16 elements.
Initializing Arrays
Arrays can also be initialized with values. For example, we could initialize an array of integers with the
values 1, 2, and 3 like this:
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