Python快速入门

时间：2010-10-17 来源：Aixe

# 注释 # This is a annotation

# 变量和赋值

v = "Hello World"

# print格式化输出

print(v)
print("The length of (%s) is %d" %(v, len(v)))
print("dec: %d, oct: %o, hex: %x, float: %5f" %(64,64,64,64))

# 使用str函数将对象转化为字符串

sum = 2000
print(str(sum) + " dollas")

# 使用int函数将对象转化为数字

fund = "500"
print(int(fund) + 1500)

# 列表(list)

ls = ['C#', 'VB', 'C++', 'Java', 'Python', 'Ruby']
print(ls)
print(ls[0])

# 字典(dictionary)

dic = {1:'John', 2:'Jane', 3:'Jack', 4:'James', 5:'Julie'}
print(dic)
print(dic[1])

# 简单的循环

for i in range(0,5): print(i)
for v in ls: print(v)
for k in dic: print("%s: %s" %(str(k), dic[k]))

# range函数

r1 = range(1,10) # 从1到10(不包括10)，步长为1
for i in r1: print(i)

r2 = range(-1,-20,-2) # 从-1到-20(不包括-20)，步长为-2
for j in r2: print(j)

# 条件判断

x = int(input("enter an integer: "))
if x==0:
    print("zero")
elif x<0:
    print("negative")
else:
    print("positive")

# 定义函数

def sum(a, b): return a + b;
def inc(a, b=0): return a + b;
print(sum(1, 99)) # return 100
print(inc(1, 99)) # return 100
print(inc(100)) # return 100

# 异常处理

s = input("Type something: ")
if s=="":
    raise Exception("You must input something...")

try:
    print(int(s))
except Exception as err:
    print(err)
finally:
    print("Bye Bye!")

# 简单的文件处理

代码 data = [1, 1, 2, 3, 5, 8, 13, 21, 34, 55]
path = "abc.txt"

fw = open(path, "w")    # 使用写方式打开，文件不存在则创建
fw.write("The Fibonacci:\n")
for i in range(0, len(data)):
    if i < len(data) - 1: fw.write("%d, " %(data[i]))
    else: fw.write("%d..." %(data[i]))
fw.close()    # 表忘记关闭文件

fo = open(path, "r")    # 使用读方式打开文件
for line in fo: print(line)
fo.close()    # 表忘记关闭文件