This document provides an introduction to arrays and pointers for beginner programmers. It explains what arrays and pointers are, how to declare and initialize them, and includes examples of common operations like accessing element values, taking addresses, and dereferencing pointers. Demo code is provided to illustrate summing array elements, finding maximum values, reversing an array, and printing two-dimensional arrays and pointers. The document aims to explain basic array and pointer concepts without advanced mathematics to help beginners learn programming fundamentals.

1. Placement Preparation
Arrays & Pointers
Shobhit Chaurasia
B.Tech, CSE

2. Target Audience
People who have no prior coding experience, didn’t take
CS101 seriously but want to learn some basics of coding
quickly.
If you know how write a program to sum up numbers in an
array, and you DO NOT faint on seeing int ***ptr, then
please don’t your waste time here; this tutorial is not for
you.

3. Data types
● int : -1000, -5, 0, 10, 2014
● char : a, @, +
● float : -10.35, 2.578
● bool : True/False

4. More Data types
● Array - {1,2,3,4}
● String - “Ghissu”
● Pointers

5. Arrays
● Array is a collection of objects.

6. Arrays - 1D
● int test[10]; // space for 10 ints
● 0-based indexing
● Index from 0 to (size - 1)

7. Array - initialization
1D
2D

8. Demo #1
Store first 10 +ve integers in an array and
print them.

9. Demo #2
Sum up all the numbers in an array.

10. Demo #3
Find the max. number in an array.

11. Demo #4
Reverse the contents of an array.
int arr[10]={1,2,3,4,5,6,7,8,9,10};

12. Arrays - 2D (Matrix)
● int test_score[x][y]
Row Index
Column Index
int test_score[10][4]

13. Demo #5
Output contents of a 2D int array.

14. Demo #6
char mat[6][3];
0 1 2
0 e o e
1 o e o
2 e o e
3 o e o
4 e o e
5 o e o

15. Arrays - 3D

16. Address of Variables
● int x = 10; //value of x is 10
● address of variable x is &x
x
10
0x7fff4d84231c
Variable Name
Data/Content
Address of variable

17. Demo #7
Print the value and address of a float

18. Pointers
Pointer is a variable that contains memory
address.
ptr
0x7fff4d84231c
p
0x7fff01f8239c
f
0x00abcd12209

19. ptr
0x7fff4d84231c
p
f
0x243f01f8239a 0x00abcd12209
10
0x7fff4d84231c
s
0x243f01f8239a
0.3
0x00abcd12209

21. Demo #8
&x returns the
address of
variable x

22. Pointer Dereferencing
int *ptr;
ptr = &x;
cout<<ptr;
cout<<*ptr;
Pointer Declaration
Making ptr point to x (x MUST be int)
Will print address of x
Will print the value stored at x
6
0x7fff4d84231c
ptr
x

23. Pointer Dereferencing
*ptr returns the value stored at the memory
location pointed to by ptr

24. Demo #9
➔ Show and explain 9.cpp
➔ Ask them to reproduce the code without looking

25. NULL Pointer
int *ptr = NULL; //good coding practice
ptr

26. Pointer to Pointer
int x = 10;
int *p = &x;
int **q = &p;
q
0x32
0x74
p
0x66
0x32
x
10
0x66

27. Arrays as pointers
int arr[7];
Array Index
Data
arr
0 1 2 3 4 5 6
- 22 - 33 - 44 - 55 - 66 - 77 - 88
0014 0018 0022 0026 0030 0034 0038
arr + 1 arr +2 arr + 6
Address

28. 0 1 2 3 4 5 6
- 22 - 33 - 44 - 55 - 66 - 77 - 88
0014 0018 0022 0026 0030 0034 0038
arr[0] is same as *(arr + 0) is same as -22
&(arr[0]) is same as (arr + 0) is same as 0014
arr[1] is same as *(arr + 1) is same as -33
&(arr[1]) is same as (arr + 1) is same as 0018
arr[5] is same as *(arr + 5) is same as -77
&(arr[5]) is same as (arr + 5) is same as 0034
Array Index
int arr[7]
Address
arr

29. To be continued ...
● Dynamic memory allocation
● C-style strings.
● strcmp, strcat etc.