Python学习笔记一:数据类型转换

原文地址为： Python学习笔记一:数据类型转换

一、int函数能够
     （1）把符合数学格式的数字型字符串转换成整数
     （2）把浮点数转换成整数，但是只是简单的取整，而非四舍五入。

举例：

1 aa = int( " 124 " ) # Correct
2   print " aa = " , aa # result=124
3   bb = int( 123.45 ) # correct
4   print " bb = " , bb # result=123
5   cc = int( " -123.45 " ) # Error,Can't Convert to int
6   print " cc = " ,cc
7 dd = int( " 34a " ) # Error,Can't Convert to int
8 print " dd = " ,dd
9 ee = int( " 12.3 " ) # Error,Can't Convert to int
10 print ee
11

二、float函数将整数和字符串转换成浮点数。

举例：

1 aa = float( " 124 " ) # Correct
2 print " aa = " , aa # result = 124.0
3 bb = float( " 123.45 " ) # Correct
4 print " bb = " , bb # result = 123.45
5 cc = float( - 123.6 ) # Correct
6 print " cc = " ,cc # result = -123.6
7 dd = float( " -123.34 " ) # Correct
8 print " dd = " ,dd # result = -123.34
9 ee = float( ' 123v ' ) # Error,Can't Convert to float
10 print ee

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三、str函数将数字转换成字符

举例：

1 aa = str( 123.4 ) # Correct
2 print aa # result = '123.4'
3 bb = str( - 124 .a) # SyntaxError: invalid syntax
4 print bb
5 cc = str( " -123.45 " ) # correct
6 print cc # result = '-123.45'
7 dd = str( ' ddd ' ) # correct
8 print dd # result = ddd
9 ee = str( - 124.3 ) # correct
10 print ee # result = -124.3

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