88 lines
4.0 KiB
Markdown
88 lines
4.0 KiB
Markdown
---
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title: Data Structure Arrays
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---
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Internally, `array` is a kind of data structure that 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.
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`array` consists of contiguous memory locations. The lowest address corresponds to the first element and the highest address to the last element.
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## Arrays in C++
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C++ provides a data structure, `array`, which stores a fixed-size sequential collection of elements of the same data-type. An `array` is used to store a collection of data, but it is better to think of an `array` as a collection of variables of the same type.
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#### Declaration of `array`
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int intarray[10]; // Declares an array of integer type of size 10 with elements having random values. Index ranges from 0 to 9(i.e. size-1).
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int intarray[10] = { 0 }; // Declares an array of integer of size 10 with all elements having value 0
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// Choose one the two declarations and then move ahead.
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#### Inserting elements to `array`:
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intarray[0] = 1; // Inserts an integer value of 1 at index 0
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intarray[1] = 0; // Inserts an integer value of 0 at index 1
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intarray[2] = -1; // Inserts an integer value of -1 at index 2
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intarray[3] = 1; // Inserts an integer value of 1 at index 3
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#### Printing an `array`:
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std::cout << intarray[0] << std::endl; // Returns 1 which is element at index of the array
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std::cout << intarray[11] << std::endl; // Would give a a "Garbage" value as there is no element at index 11 of array.
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// That memory location is beyond the range of the array.
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// To print all the elements of the array
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for(int i = 0; i < n; i++)
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std::cout << intarray[i] << std::endl;
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#### Basic operations on `array`:
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std::cout << sizeof(intarray)/sizeof(intarray[0]) << std::endl; // Returns the length of the array i.e. 10.
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std::cout << sizeof(intarray[0]) << std::endl; // Returns length in bytes of one array item i.e. 4 as it is an integer
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:rocket: [Run Code](https://repl.it/CWZE/3)
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## Arrays in Python
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Python doesn't have a native `array` data structure. An `array` in Python should not be confused with `list`. The major difference between a `list` and an `array` in Python is that a `list` can have different types of values whereas an `array` should have all the values of same type.
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#### Declaration of `array`
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from array import array
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intarray = array('i') # Declares an array of integer type
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#### Inserting elements to `array`:
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intarray.append(1) # Inserts an integer value of 1 to the array
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intarray.append(0) # Inserts an integer value of 0 to the array
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intarray.append(-1) # Inserts an integer value of -1 to the array
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intarray.append(1) # Inserts an integer value of 1 to the array
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intarray.append('d') # Would give a TypeError as the array is of integer type.
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#Resolve the above error and then move ahead.
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#### Printing an `array`:
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print(intarray) # Returns array('i', [1, 4, -1])
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print(intarray[0]) # Returns 1 which is the element at index 0 of the array
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print(intarray[3]) # Would give IndexError as there is no element at index 3 of array.
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#Resolve the above error and then move ahead.
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# To print all the elements of the array
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for i in intarray:
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print(i)
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#### Basic operations on `array`:
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len(intarray) # Returns the length of the array i.e. 3
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intarray.itemsize # Returns length in bytes of one array item i.e. 4 as it is an integer
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intarray.count(1) # Returns the number of occurrences of 1 in the array i.e. 2
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intarray.insert(1, 3) # Insert a new item with value x in the array before position i
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intarray.remove(1) # Remove the first occurrence of 1 from the array
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intarray.reverse() # Reverse the order of the items in the array
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intarray.pop(1) # Removes the item with the index 1 from the array and returns it
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:rocket: [Run Code](https://repl.it/CWJB)
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<a href='https://docs.python.org/3.5/library/array.html' target='_blank' rel='nofollow'>Official Docs</a>
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