add code of 04

Author: qiwsir

python3code/chapter03/parabola.py

@@ -1,4 +1,7 @@
 # coding:utf-8
+'''
+filename: parabola.py
+'''
 
 def parabola(a, b, c):
     def para(x):

python3code/chapter04/addfractions.py

@@ -0,0 +1,36 @@
+#coding:utf-8
+'''
+filename: addfractions.py
+'''
+
+def gcd(a, b):
+    if not a > b:
+        a, b = b, a
+    while b != 0:
+        remainder = a % b
+        a, b = b, remainder
+    return a
+
+def lcm(a, b):
+    return (a * b) / gcd(a,b)
+
+class Fraction:
+    def __init__(self, number, denom=1):
+        self.number = number
+        self.denom = denom
+
+    def __str__(self):
+        return str(self.number) + '/' + str(self.denom)
+
+    __repr__ = __str__
+
+    def __add__(self, other):
+        lcm_num = lcm(self.denom, other.denom)
+        number_sum = (lcm_num / self.denom * self.number) + (lcm_num / other.denom * other.number)
+        return Fraction(number_sum, lcm_num)
+
+if __name__ == "__main__":
+    m = Fraction(1, 3)
+    n = Fraction(1, 2)
+    s = m + n
+    print(m,"+",n,"=",s)

python3code/chapter04/convert2g.py

@@ -0,0 +1,13 @@
+#coding:utf-8
+'''
+filename: convert2g.py
+'''
+
+class ToGram(float):
+    def __new__(cls, jin=0.0):
+        gram = jin / 2 * 1000
+        return float.__new__(cls, gram)
+
+jin = 2.3
+value = ToGram(jin)
+print("{0}jin = {1:.2f}g".format(jin, value)) 

python3code/chapter04/definefraction.py

@@ -0,0 +1,18 @@
+#coding:utf-8
+'''
+filename: definefraction.py
+'''
+class Fraction:
+    def __init__(self, number, denom=1):
+        self.number = number
+        self.denom = denom
+
+    def __str__(self):
+        return str(self.number) + '/' + str(self.denom)
+
+    __repr__ = __str__
+
+
+if __name__ == "__main__":
+    f = Fraction(2, 3)
+    print(f)

python3code/chapter04/fibsyield.py

@@ -0,0 +1,16 @@
+# coding:utf-8
+'''
+filename: fibsyield.py
+'''
+
+def fibs(max):
+    n, a, b = 0, 0, 1
+    while n < max:
+        yield b
+        a, b = b, a + b
+        n = n + 1
+
+if __name__ == "__main__":
+    f = fibs(10)
+    for i in f:
+        print(i, end=',')

python3code/chapter04/gcdlcm.py

@@ -0,0 +1,19 @@
+#coding:utf-8
+'''
+filename: gcdlcm.py
+'''
+
+def gcd(a, b):        #最大公约数
+    if not a > b:
+        a, b = b, a
+    while b != 0:
+        remainder = a % b
+        a, b = b, remainder
+    return a
+
+def lcm(a, b):        #最小公倍数
+    return (a * b) / gcd(a,b)
+
+if __name__ == "__main__":
+    print(gcd(8, 20))
+    print(lcm(8, 20))

python3code/chapter04/mro.py

@@ -0,0 +1,27 @@
+# coding:utf-8
+
+class K1:
+    def foo(self):
+        print("K1-foo")
+
+class K2:      
+    def foo(self):
+        print("K2-foo")
+    def bar(self):
+        print("K2-bar")
+
+class J1(K1, K2):
+    pass
+
+class J2(K1, K2):
+    def bar(self):
+        print("J2-bar")
+
+class C(J1, J2):
+    pass
+
+if __name__ == "__main__":
+    print(C.__mro__)
+    m = C()
+    m.foo()
+    m.bar()

python3code/chapter04/multi_inhance.py

@@ -0,0 +1,23 @@
+# coding:utf-8
+
+class Person: 
+    def eye(self):
+        print("two eyes")
+
+    def breast(self, n):
+        print("The breast is: ",n)
+
+class Girl:
+    age = 28
+    def color(self):
+        print("The girl is white")
+
+class HotGirl(Person, Girl):
+    pass
+
+if __name__ == "__main__":
+    kong = HotGirl()
+    kong.eye()
+    kong.breast(90)
+    kong.color()
+    print(kong.age)

python3code/chapter04/myrange.py

@@ -0,0 +1,24 @@
+# coding:utf-8
+'''
+filename: myrange.py
+'''
+
+class MyRange:
+    def __init__(self, n):
+        self.i = 1
+        self.n = n
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        if self.i <= self.n:
+            i = self.i
+            self.i += 1
+            return i
+        else:
+            raise StopIteration()
+
+if __name__ == "__main__":
+    x = MyRange(7)
+    print([i for i in x])

python3code/chapter04/private.py

@@ -0,0 +1,18 @@
+# coding:utf-8
+
+class ProtectMe: 
+    def __init__(self):
+        self.me = "qiwsir"
+        self.__name = "kivi"
+
+    def __python(self):
+        print("I love Python.")
+
+    def code(self):
+        print("Which language do you like?")
+        self.__python()
+
+if __name__ == "__main__":
+    p = ProtectMe()
+    print(p.me)
+    print(p.__name)