http://www.cnblogs.com/dabiao/archive/2010/03/07/1680096.html
我又土了，，，都是用string.atoi之类的实现的
aa = int("124") #Correct
print "aa = ", aa #result=124
bb = int(123.45) #correct
print "bb = ", bb #result=123
cc = int("-123.45") #Error,Can't Convert to int
print "cc = ",cc
dd = int("34a") #Error,Can't Convert to int
print "dd = ",dd
ee = int("12.3") #Error,Can't Convert to int
print ee
print int('f') #error
print int('f',16) 15#用16进制的标准解析
aa = float("124") #Correct
print "aa = ", aa #result = 124.0
bb = float("123.45") #Correct
print "bb = ", bb #result = 123.45
cc = float(-123.6) #Correct
print "cc = ",cc #result = -123.6
dd = float("-123.34") #Correct
print "dd = ",dd #result = -123.34
ee = float('123v') #Error,Can't Convert to float
print ee
aa = str(123.4) #Correct
print aa #result = '123.4'
bb = str(-124.a) #SyntaxError: invalid syntax
print bb
cc = str("-123.45") #correct
print cc #result = '-123.45'
dd = str('ddd') #correct
print dd #result = ddd
ee = str(-124.3) #correct
print ee #result = -124.3
int(x [,base ]) 将x转换为一个整数
long(x [,base ]) 将x转换为一个长整数
float(x ) 将x转换到一个浮点数
complex(real [,imag ]) 创建一个复数
str(x ) 将对象 x 转换为字符串
repr(x ) 将对象 x 转换为表达式字符串
eval(str ) 用来计算在字符串中的有效Python表达式,并返回一个对象
tuple(s ) 将序列 s 转换为一个元组
list(s ) 将序列 s 转换为一个列表
chr(x ) 将一个整数转换为一个字符 range [0..255]
unichr(x ) 将一个整数转换为Unicode字符 unichr(0x6211) ‘我’的unicode是6211
ord(x ) 将一个字符转换为它的整数值
hex(x ) 将一个整数转换为一个十六进制字符串
oct(x ) 将一个整数转换为一个八进制字符串