Python basic data Type (iii)-string concatenation-formatted output-dark copy-python3 notes

1. String concatenation

2. Formatted output

3. God copy and shallow copy

1. String concatenation

Example: a= ' Hello ', b= ' python ', c= '! ' Connect the strings in the a,b,c to a single sentence. 1. A+b+c2 with + number. Format string% '%s%s '% (a,b,c) 3. '. Join () method, note that the brackets are to be connected (can be list, Ganso) '. Join ([a,b,c]) # ' Inside is the character 4 of each string after the connection. The Format method ' {}{}{} '. Format (a,b,c) #{} can be filled with the corresponding symbol in the following format: ' {}{}{} '. Format (A,b,c) when {} is empty, the default index is 0, Enter ' {1}{2}{0} ' in the order of the format brackets. Format (A,B,C) when there is an index value in {}, each subsequent item is filled in ' {n1}{n2}{n3} ' by the previous index value. Format (n1=a,n2=b,n3=c {} You can specify the object name, followed by assigning values to the preceding corresponding value, followed by unordered >>> a,b,c= ' i ', ' love ', ' Python ' #定义字符串 >>> print (a,b,c) I Love python>>> a= ' i '; b= ' love ' #定义字符串 >>> print (A, b) I love plus splicing: >>> a+b+c ' Ilovepyt Hon ' >>> A + ' +b+ ' +c ' I love python ' >>> A + ' +b+ ' * * * * * * +c ' i love**** python ' formatted string % (placeholder) >>> '%s '% 2 ' 2 ' >>> '%s%s%s '% (a,b,c) ' Ilovepython ' >>> '%s '%s '% ( a,b,c) ' I love Python ' >>> '%s%s * *%s '% (a,b,c) ' I love * * python ' >>> '%s +%s =%s '% (1 , 2,3) ' 1 + 2 =3 '. JOin () Method: >>> Help (". Join)" On built-in function Join:join (...) Methods of Builtins.str instance  S.join (iterable), str Return A string which is the concatenation of the strings in the iterable.     The separator between elements is S. >>> '. Join ([a,b,c]) ' Ilovepython ' >>> '. Join ([a,b,c]) ' I love python ' >>> ' * '. Jo In ([A,b,c]) ' I*love*python ' >>> ' * '. Join ((a,b,c)) ' I*love*python '. Format mode: >>> Help (". Form AT) Help on built-in function Format:format (...) method of Builtins.str instance S.format (*args, **kwargs)-        > str Return A formatted version of S, using substitutions from args and Kwargs.    The substitutions is identified by braces (' {' and '} '). >>> print (a,b,c) I love python >>> ' {}{}{} '. Format (a,b,c) ' Ilovepython ' >>> ' {} {} {} '. Format (a,b,c) ' I love python ' >>> ' {0} {1} {2} '. foRmat (a,b,c) #默认索引位置为0, ' I love python ' >>> ' {1} {2} {0} '. Format (a,b,c) #调换索引位置 ' Love Python I ' & Gt;>> ' {0[0]} {0[1]} {0[2]} '. Format ([a,b,c]) ' I love python ' >>> ' {n1} {N2} {n3} '. Format (n1=a,n2=b,n3  =c) ' I love python ' >>> ' {n1} {n3} {n2} '. Format (n1=a,n2=b,n3=c) ' I python love ' #format补充 >>> ' {:. 1f} '. Format (12.2222) #保留1位小数 ' 12.2 ' >>> ' {:. 2%} '. Format (12.22222) #百分比 ' 1222.22% ' & Gt;>> ' {:. 2%} '. Format (. 222222) #百分比 ' 22.22% ' >>> ' {:. 2%} '. Format (0.222222) #百分比 ' 22.22% ' >>> ' {: <10} '. Format (#输出10位占位, left-aligned '-' >>> ' {: >10} '. Format     #输出10位占位, alignment ' >>> ' {: ^10} '. Format #输出10位占位, centered, 5 each on each side ' 12 ' >>> ' {:* ^10} '. Format #用 * To populate the placeholder ' ****12**** '

2. Formatted output

%s formatted string%d formatted integer%f formatted decimal%c formatted ASCII character%o Format octal%x formatted hexadecimal%e with science and technology format-used as left-aligned + display plus m,n m is the minimum length to display when M is greater than the format number, and n represents the decimal bit transfer character: \ nthe newline \a beep (required in Windows cm  Python in D uses) \b Backspace (required for Python in Windows cmd) \ t Horizontal tab Natural string R ' #格式化字符串 >>> '%s '% 1 ' 1 ' >>> '%s '% ' licky ' licky ' >>> '%10s '% ' lucky ' #10表示字符串的宽度, default right alignment ' lucky ' >>> '%-10 S '% ' lucky ' #-= left aligned ' lucky# formatted integer >>> '%d '% 1 ' 1 ' >>> '%d '% 1.1 ' 1 ' &G T;>> '%d '%-1 '-1 ' #格式化小数 >>> '%f '% 1.22 ' 1.220000 ' >>> '%.3f '% 1.2 #.3 reserved decimal point 3 bits ' 1.200 ' >>> '%2.3f '% 234.1 #指定宽度与实际整数部分宽度冲突以实际输出 ' 234.100 ' >>> '%3.5f '% 1.5 #     Width and progress conflict, followed by precision ' 1.50000 ' >>> '%10.3f '% 1.4 ' 1.400 ' >>> '%-10.3f '% 1.3 ' 1.300 ' #格式化ASCII字符 >>> '%c '% ' a ' >>> '%c '% ' a ' #格式化八进制 >>> '%o '% 8 ' >>> '%o '% 6 ' 6 ' >>> '%o '% + ' #格式化十六进制 >>> '%x '% 16 ' Ten ' >>> '%x '% ' + ' >>> '%x '% ' a ' >>> '%x '% One ' b ' >>> '%     X '% ' F ' #用科学技术法格式化 >>> '%e '% #10的2次方 ' 1.000000e+02 ' >>> '%e '% #10的3次方 ' 1.000000e+03 ' #\n line >>> print (' aaaa\n ') AAAA >>> #\t horizontal tab >>> print (' aaa\tbbb ' ) #\t represents a TAB key. A tab==4 space AAA bbb# Natural String R ' is also called the original string, de-escaping >>> print (R ' aaa\baaa ') aaa\baaa >>> print (' aaa\ \baaa ') aaa\baaa

3. Albums: deep copy and shallow copy (nested between Ganso and list)

1.元祖和列表之间的相互嵌套(字符串里面都会变成字符串，失去列表和元祖的方法)2.嵌套之后可以通过索引值来去数3.浅复制4.深复制5.那些是浅复制 copy 切片#浅复制    >>> li=[1]    >>> id(li)    47093800    >>> li1=li.copy()    >>> id(li1)    47094840    >>> li = [‘a‘,‘b‘]    >>> li_1 = [1,li]    >>> li_1    [1, [‘a‘, ‘b‘]]    >>> lq = li_1.copy()    >>> lq    [1, [‘a‘, ‘b‘]]    >>> li.append(‘c‘)    >>> lq    [1, [‘a‘, ‘b‘, ‘c‘]]    >>> id(li)    46524336    >>> id(lq[1])    46524336#深复制    >>> import copy    >>> ls = copy.deepcopy(li_1)    >>> ls    [1, [‘a‘, ‘b‘, ‘c‘]]    >>> li    [‘a‘, ‘b‘, ‘c‘]    >>> li.append(‘d‘)    >>> ls    [1, [‘a‘, ‘b‘, ‘c‘]]    >>> id(li)    46524336    >>> id(ls[1])    47011280

Python basic data Type (iii)-string concatenation-formatted output-dark copy-python3 notes