The "99 bottles of beer" algorithm

This example examines the implementation of the classic "99 bottles of beer" algorithm in Julia, which outputs a text song with a decreasing number of bottles.

Introduction

What is the "99 bottles of beer" algorithm?

The "99 bottles of beer" algorithm is a popular learning task in programming, which consists in outputting the text of a famous children's song with a decreasing number of bottles. Each verse of the song is repeated with a different number of bottles, starting with 99 and ending with 1. This task is used to demonstrate loops, string operations, and formatted output in various programming languages.

The source code

Let's look at the source code of the Julia program, which implements the "99 bottles of beer" algorithm:

# Цикл от 99 до 1 с шагом -1 (обратный отсчет)
for i = 99:-1:1 
    # Выводим куплет песни с текущим числом бутылок
    print("\n$i bottles of beer on the wall\n$i bottles of beer\nTake one down, pass it around\n$(i-1) bottles of beer on the wall\n") 
end

99 bottles of beer on the wall
99 bottles of beer
Take one down, pass it around
98 bottles of beer on the wall

98 bottles of beer on the wall
98 bottles of beer
Take one down, pass it around
97 bottles of beer on the wall

97 bottles of beer on the wall
97 bottles of beer
Take one down, pass it around
96 bottles of beer on the wall

96 bottles of beer on the wall
96 bottles of beer
Take one down, pass it around
95 bottles of beer on the wall

95 bottles of beer on the wall
95 bottles of beer
Take one down, pass it around
94 bottles of beer on the wall

94 bottles of beer on the wall
94 bottles of beer
Take one down, pass it around
93 bottles of beer on the wall

93 bottles of beer on the wall
93 bottles of beer
Take one down, pass it around
92 bottles of beer on the wall

92 bottles of beer on the wall
92 bottles of beer
Take one down, pass it around
91 bottles of beer on the wall

91 bottles of beer on the wall
91 bottles of beer
Take one down, pass it around
90 bottles of beer on the wall

90 bottles of beer on the wall
90 bottles of beer
Take one down, pass it around
89 bottles of beer on the wall

89 bottles of beer on the wall
89 bottles of beer
Take one down, pass it around
88 bottles of beer on the wall

88 bottles of beer on the wall
88 bottles of beer
Take one down, pass it around
87 bottles of beer on the wall

87 bottles of beer on the wall
87 bottles of beer
Take one down, pass it around
86 bottles of beer on the wall

86 bottles of beer on the wall
86 bottles of beer
Take one down, pass it around
85 bottles of beer on the wall

85 bottles of beer on the wall
85 bottles of beer
Take one down, pass it around
84 bottles of beer on the wall

84 bottles of beer on the wall
84 bottles of beer
Take one down, pass it around
83 bottles of beer on the wall

83 bottles of beer on the wall
83 bottles of beer
Take one down, pass it around
82 bottles of beer on the wall

82 bottles of beer on the wall
82 bottles of beer
Take one down, pass it around
81 bottles of beer on the wall

81 bottles of beer on the wall
81 bottles of beer
Take one down, pass it around
80 bottles of beer on the wall

80 bottles of beer on the wall
80 bottles of beer
Take one down, pass it around
79 bottles of beer on the wall

79 bottles of beer on the wall
79 bottles of beer
Take one down, pass it around
78 bottles of beer on the wall

78 bottles of beer on the wall
78 bottles of beer
Take one down, pass it around
77 bottles of beer on the wall

77 bottles of beer on the wall
77 bottles of beer
Take one down, pass it around
76 bottles of beer on the wall

76 bottles of beer on the wall
76 bottles of beer
Take one down, pass it around
75 bottles of beer on the wall

75 bottles of beer on the wall
75 bottles of beer
Take one down, pass it around
74 bottles of beer on the wall

74 bottles of beer on the wall
74 bottles of beer
Take one down, pass it around
73 bottles of beer on the wall

73 bottles of beer on the wall
73 bottles of beer
Take one down, pass it around
72 bottles of beer on the wall

72 bottles of beer on the wall
72 bottles of beer
Take one down, pass it around
71 bottles of beer on the wall

71 bottles of beer on the wall
71 bottles of beer
Take one down, pass it around
70 bottles of beer on the wall

70 bottles of beer on the wall
70 bottles of beer
Take one down, pass it around
69 bottles of beer on the wall

69 bottles of beer on the wall
69 bottles of beer
Take one down, pass it around
68 bottles of beer on the wall

68 bottles of beer on the wall
68 bottles of beer
Take one down, pass it around
67 bottles of beer on the wall

67 bottles of beer on the wall
67 bottles of beer
Take one down, pass it around
66 bottles of beer on the wall

66 bottles of beer on the wall
66 bottles of beer
Take one down, pass it around
65 bottles of beer on the wall

65 bottles of beer on the wall
65 bottles of beer
Take one down, pass it around
64 bottles of beer on the wall

64 bottles of beer on the wall
64 bottles of beer
Take one down, pass it around
63 bottles of beer on the wall

63 bottles of beer on the wall
63 bottles of beer
Take one down, pass it around
62 bottles of beer on the wall

62 bottles of beer on the wall
62 bottles of beer
Take one down, pass it around
61 bottles of beer on the wall

61 bottles of beer on the wall
61 bottles of beer
Take one down, pass it around
60 bottles of beer on the wall

60 bottles of beer on the wall
60 bottles of beer
Take one down, pass it around
59 bottles of beer on the wall

59 bottles of beer on the wall
59 bottles of beer
Take one down, pass it around
58 bottles of beer on the wall

58 bottles of beer on the wall
58 bottles of beer
Take one down, pass it around
57 bottles of beer on the wall

57 bottles of beer on the wall
57 bottles of beer
Take one down, pass it around
56 bottles of beer on the wall

56 bottles of beer on the wall
56 bottles of beer
Take one down, pass it around
55 bottles of beer on the wall

55 bottles of beer on the wall
55 bottles of beer
Take one down, pass it around
54 bottles of beer on the wall

54 bottles of beer on the wall
54 bottles of beer
Take one down, pass it around
53 bottles of beer on the wall

53 bottles of beer on the wall
53 bottles of beer
Take one down, pass it around
52 bottles of beer on the wall

52 bottles of beer on the wall
52 bottles of beer
Take one down, pass it around
51 bottles of beer on the wall

51 bottles of beer on the wall
51 bottles of beer
Take one down, pass it around
50 bottles of beer on the wall

50 bottles of beer on the wall
50 bottles of beer
Take one down, pass it around
49 bottles of beer on the wall

49 bottles of beer on the wall
49 bottles of beer
Take one down, pass it around
48 bottles of beer on the wall

48 bottles of beer on the wall
48 bottles of beer
Take one down, pass it around
47 bottles of beer on the wall

47 bottles of beer on the wall
47 bottles of beer
Take one down, pass it around
46 bottles of beer on the wall

46 bottles of beer on the wall
46 bottles of beer
Take one down, pass it around
45 bottles of beer on the wall

45 bottles of beer on the wall
45 bottles of beer
Take one down, pass it around
44 bottles of beer on the wall

44 bottles of beer on the wall
44 bottles of beer
Take one down, pass it around
43 bottles of beer on the wall

43 bottles of beer on the wall
43 bottles of beer
Take one down, pass it around
42 bottles of beer on the wall

42 bottles of beer on the wall
42 bottles of beer
Take one down, pass it around
41 bottles of beer on the wall

41 bottles of beer on the wall
41 bottles of beer
Take one down, pass it around
40 bottles of beer on the wall

40 bottles of beer on the wall
40 bottles of beer
Take one down, pass it around
39 bottles of beer on the wall

39 bottles of beer on the wall
39 bottles of beer
Take one down, pass it around
38 bottles of beer on the wall

38 bottles of beer on the wall
38 bottles of beer
Take one down, pass it around
37 bottles of beer on the wall

37 bottles of beer on the wall
37 bottles of beer
Take one down, pass it around
36 bottles of beer on the wall

36 bottles of beer on the wall
36 bottles of beer
Take one down, pass it around
35 bottles of beer on the wall

35 bottles of beer on the wall
35 bottles of beer
Take one down, pass it around
34 bottles of beer on the wall

34 bottles of beer on the wall
34 bottles of beer
Take one down, pass it around
33 bottles of beer on the wall

33 bottles of beer on the wall
33 bottles of beer
Take one down, pass it around
32 bottles of beer on the wall

32 bottles of beer on the wall
32 bottles of beer
Take one down, pass it around
31 bottles of beer on the wall

31 bottles of beer on the wall
31 bottles of beer
Take one down, pass it around
30 bottles of beer on the wall

30 bottles of beer on the wall
30 bottles of beer
Take one down, pass it around
29 bottles of beer on the wall

29 bottles of beer on the wall
29 bottles of beer
Take one down, pass it around
28 bottles of beer on the wall

28 bottles of beer on the wall
28 bottles of beer
Take one down, pass it around
27 bottles of beer on the wall

27 bottles of beer on the wall
27 bottles of beer
Take one down, pass it around
26 bottles of beer on the wall

26 bottles of beer on the wall
26 bottles of beer
Take one down, pass it around
25 bottles of beer on the wall

25 bottles of beer on the wall
25 bottles of beer
Take one down, pass it around
24 bottles of beer on the wall

24 bottles of beer on the wall
24 bottles of beer
Take one down, pass it around
23 bottles of beer on the wall

23 bottles of beer on the wall
23 bottles of beer
Take one down, pass it around
22 bottles of beer on the wall

22 bottles of beer on the wall
22 bottles of beer
Take one down, pass it around
21 bottles of beer on the wall

21 bottles of beer on the wall
21 bottles of beer
Take one down, pass it around
20 bottles of beer on the wall

20 bottles of beer on the wall
20 bottles of beer
Take one down, pass it around
19 bottles of beer on the wall

19 bottles of beer on the wall
19 bottles of beer
Take one down, pass it around
18 bottles of beer on the wall

18 bottles of beer on the wall
18 bottles of beer
Take one down, pass it around
17 bottles of beer on the wall

17 bottles of beer on the wall
17 bottles of beer
Take one down, pass it around
16 bottles of beer on the wall

16 bottles of beer on the wall
16 bottles of beer
Take one down, pass it around
15 bottles of beer on the wall

15 bottles of beer on the wall
15 bottles of beer
Take one down, pass it around
14 bottles of beer on the wall

14 bottles of beer on the wall
14 bottles of beer
Take one down, pass it around
13 bottles of beer on the wall

13 bottles of beer on the wall
13 bottles of beer
Take one down, pass it around
12 bottles of beer on the wall

12 bottles of beer on the wall
12 bottles of beer
Take one down, pass it around
11 bottles of beer on the wall

11 bottles of beer on the wall
11 bottles of beer
Take one down, pass it around
10 bottles of beer on the wall

10 bottles of beer on the wall
10 bottles of beer
Take one down, pass it around
9 bottles of beer on the wall

9 bottles of beer on the wall
9 bottles of beer
Take one down, pass it around
8 bottles of beer on the wall

8 bottles of beer on the wall
8 bottles of beer
Take one down, pass it around
7 bottles of beer on the wall

7 bottles of beer on the wall
7 bottles of beer
Take one down, pass it around
6 bottles of beer on the wall

6 bottles of beer on the wall
6 bottles of beer
Take one down, pass it around
5 bottles of beer on the wall

5 bottles of beer on the wall
5 bottles of beer
Take one down, pass it around
4 bottles of beer on the wall

4 bottles of beer on the wall
4 bottles of beer
Take one down, pass it around
3 bottles of beer on the wall

3 bottles of beer on the wall
3 bottles of beer
Take one down, pass it around
2 bottles of beer on the wall

2 bottles of beer on the wall
2 bottles of beer
Take one down, pass it around
1 bottles of beer on the wall

1 bottles of beer on the wall
1 bottles of beer
Take one down, pass it around
0 bottles of beer on the wall

Analyzing how the code works

Cycle for i = 99:-1:1 means that the variable i it will take values from 99 to 1 in increments of -1 (i.e. decrease by one at each step). In the body of the loop using the function print() The verse of the song is formed and displayed. String interpolations are used $i \text{и} $(i-1) to substitute the current and next values of a variable i.

Implementation features

In this implementation:

A decreasing counter cycle is used to simulate a countdown.
String interpolation is used to dynamically insert numbers into the text.
Each verse is output in one line using escaped characters. \n.

Conclusion

In this example, we looked at the implementation of the classic algorithm "99 bottles of beer" in the Julia language. We managed to create a program that outputs a text song with a decreasing number of bottles using a loop and string interpolation. This is necessary to demonstrate the basic features of the Julia language for working with loops, strings, and formatted output.

The example was developed using materials from Rosetta Code