# boo 0.8.2

Version of implementation Boo of programming language Boo

A version of Boo language, released on May 19, 2008.

## Examples:

### Hello, World! - Boo (246):

``````print("Hello, World!")
``````

### Factorial - Boo (247):

This example uses recursive factorial definition. The function `factorial` is called recursively, so it needs an explicit declaration of its return type.

``````def factorial(n as long) as long:
if n == 0:
return 1
else:
return n * factorial(n - 1)

for n in range(0, 17):
print("\${n}! = \${factorial(n)}")
``````

### Factorial - Boo (248):

This example uses iterative factorial definition. Variable `fact` needs an explicit type declaration, since otherwise it will be typed as `int`, and trying to calculate 13! will cause an overflow error.

``````fact as long = 1
for i in range(17):
print("\${i}! = \${fact}")
fact = fact * (i+1)
``````

### Fibonacci numbers - Boo (249):

This example uses iterative definition of Fibonacci numbers. The array `a` is declared to have 16 elements right away, and the elements are calculated later.

``````a = array(int, 16)
a = a = 1
for i in range(2,16):
a[i] = a[i-1] + a[i-2]
s=""
for i in range(16):
s = s + a[i] + ", "
print(s + "...")
``````

### Fibonacci numbers - Boo (250):

This example shows the usage of generator `fib`: it initializes inner variables `a` and `b`, and after each call to generator it updates the variables and returns one of them. Function `zip` is a built-in which returns an IEnumerable that is a “mesh” of two IEnumerables — `range` and `fib`.

``````def fib():
a, b = 0, 1
while true:
yield b
a, b = b, a + b

s=""
for i, n in zip(range(16), fib()):
s = s+n+", "
print(s+"...")
``````

### Quadratic equation - Boo (276):

``````A = int.Parse(prompt("A = "))
if A==0 :
print "Not a quadratic equation."
return
B = int.Parse(prompt("B = "))
C = int.Parse(prompt("C = "))
D = B*B-4*A*C
if D==0 :
x = -0.5*B/A
print "x = \${x}"
return
if D>0 :
x1 = 0.5*(-B-System.Math.Sqrt(D))/A
x2 = 0.5*(-B+System.Math.Sqrt(D))/A
print "x1 = \${x1}"
print "x2 = \${x2}"
else :
r = -0.5*B/A
i = 0.5*System.Math.Sqrt(-D)/System.Math.Abs(A)
print "x1 = (\${r},\${i})"
print "x2 = (\${r},-\${i})"

``````