Python基础（数字,字符串方法）

1 #二进制转十进制
2 a=‘100‘
3 v=int(a,base=2)
4 print(v)

1 #当前数字的二进制至少有多少位
2 b=2
3 v2=b.bit_length()
4 print(v2)

1 #首字母大写
2 a="kelvin"
3 v=a.capitalize()
4 print(v)

1 #终极无敌‘大写‘变‘小写‘---->casefold
2 b="KELVIN"
3 v1=b.casefold()
4 v2=b.lower()
5 print(v1)
6 print(v2)

1 #居中显示字符串
2 c="kelvin"
3 v3=c.center(50,"-") #第二个参数不填，默认空格
4 print(v3)

1 #查询在字符串中指定序列出现次数
2 d="kelvinvinkddq"
3 num=d.count("d")
4 print(num)

 1 #判断是否以指定字符序列开头或者结尾
 2 e="nihaoyahahakelvin"
 3 v4=e.endswith("in")
 4 v6=e.endswith("o")
 5 v5=e.startswith("ni")
 6 v7=e.startswith("ll")
 7 print(v4)
 8 print(v6)
 9 print(v5)
10 print(v7)

1 #查找字符串中是否有指定序列
2 f="fsdhjheujfdkelvinvfs d"
3 num1=f.find("kelvin")
4 num2=f.find("fsdf")
5 print(num1)
6 print(num2)

1 #字符串格式化
2 g="i am {name},age {age}"
3 v8=g.format(name="alex",age=19)
4 v9=g.format_map({"name":"kelvin","age":21})
5 print(v8)
6 print(v9)

1 #返回指定序列索引，不存在则报错
2 a="kelvinalapplebanag"
3 v=a.index("w")
4 print(v)

1 str = "this2009";  # 字符中没有空格
2 print (str.isalnum());
3 
4 str = "this is string example....wow!!!";
5 print(str.isalnum());

1 str = "this";  # No space & digit in this string
2 print str.isalpha();
3 
4 str = "this is string example....wow!!!";
5 print str.isalpha();

1 str = "123456";  # Only digit in this string
2 print str.isdigit();
3 
4 str = "this is string example....wow!!!";
5 print str.isdigit();

1 str = "       "; 
2 print str.isspace();
3 
4 str = "This is string example....wow!!!";
5 print str.isspace();

1 tr = "This Is String Example...Wow!!!";
2 print str.istitle();
3 
4 str = "This is string example....wow!!!";
5 print str.istitle();

1 str = "-";
2 seq = ("a", "b", "c"); # 字符串序列
3 print str.join( seq );

1 str = "this is string example....wow!!!";
2 
3 print str.ljust(50, ‘0‘);

1 str = "     this is string example....wow!!!     ";
2 print str.lstrip();
3 str = "88888888this is string example....wow!!!8888888";
4 print str.lstrip(‘8‘);

 1 from string import maketrans   # 必须调用 maketrans 函数。
 2 
 3 intab = "aeiou"
 4 outtab = "12345"
 5 trantab = maketrans(intab, outtab)
 6 
 7 str = "this is string example....wow!!!";
 8 print str.translate(trantab);
 9 
10 以上实例输出结果如下：
11 
12 th3s 3s str3ng 2x1mpl2....w4w!!!

1 str = "this is really a string example....wow!!!";
2 print "Max character: " + max(str);
3 
4 str = "this is a string example....wow!!!";
5 print "Max character: " + max(str);

1  
2 str = "00000003210Runoob01230000000"; 
3 print str.strip( ‘0‘ );  # 去除首尾字符 0
4  
5  
6 str2 = "   Runoob      ";   # 去除首尾空格
7 print str2.strip();

1 str = "this is string example....wow!!!";
2 print str.swapcase();
3  
4 str = "THIS IS STRING EXAMPLE....WOW!!!";
5 print str.swapcase();