人生苦短我用python-基础部分-1.数字及字符运算

经过2016年的学习，发现自己学习的方法存在误区，听视频很费时间也不容易掌握，要直接练习书上代码，在此基础上多写程序，在进一步优化程序，把基础打牢。

一、数字运算

#常用python数字运算部分
a=9/5
b=9//5
c=5**2
d=9%5#取余
e=divmod(9,5)#商和余
print("a=",a,"b=",b,"c=",c,"d=",d,"e=",e)
print("0b10=",0b10,"0o10=",0o10,"0x10=",0x10)#二进制、八进制、16进制的10表示
print("int(99.99)=",int(99.99))#浮点转换整数
print("float(99)=",float(99))#整形转浮点
print("float(1.0e10)=",float(1.0e10))
print("float(True)=",float(True),"float(False)=",float(False))#布尔值真.假转换浮点
print("2**100=",2**100)#python 数字运算不会溢出

a= 1.8 b= 1 c 25 d 4 e= (1, 4)
0b10= 2 0o10= 8 0x10= 16
int(99.99)= 99
float(99)= 99.0
float(1.0e10)= 10000000000.0
float(True)= 1.0 float(False)= 0.0
2**100= 1267650600228229401496703205376

 二、字符运算

#单引号，双引号，三引号作用
a='zhongguo'#单引号
b="zheshi'zhongguo,shoudu'beijing"#双引号可以把单引号引入
c='''     this is an apple#三引号可以把多行文本引入
         this is a  bag
         this is a  phone
  '''
print("a=",a,"\n","b=",b,"\n","c=",c)

a= zhongguo 
b= zheshi'zhongguo,shoudu'beijing 
c=      this is an apple#三引号可以把多行文本引入
          this is a  bag
          this is a  phone

#字符转换、转意、换行及制表位
print("str(True)=",str(True),type(str(True)))#str 把其它类型转成字符
print("this \"biaoshi yinyong\" \\biaoshi zhuanyi")#\转义字符的使用
print("this is a \n apple\t \n banana \n orange \t")#\n 换行 \t 制表符

str(True)= True <class 'str'>
this "biaoshi yinyong" \biaoshi zhuanyi
this is a 
 apple     
 banana 
 orange

 

#字符常用用法
a1,b1="chifan","haochide"
print("a1=",a1,"b1=",b1,"\na1+b1=",a1+b1)#两个字符+
print("a1*4=",a1*4,"\nb1*4=",b1*4)#*用于复制字符串
print("a1[0]=",a1[0],"\nb1[1]=",b1[1])#[]字符串提取 0代表第一个-1代表最后一个
print("a1=",a1,"\na1[::-1]",a1[::-1])#[start:end:step] 从后往前
print("a1[1:4]=",a1[1:4])#范围是0-end-1
print("a1[::2]=",a1[::2])#步长为2 隔字符打
print("len(a1*4)=",len(a1*4))#测字符串长度

fenge="aa,bb,cc,dd,ee,ff,dd,gg"
fg=fenge.split(',')#分割
fg1=list(fenge)
print("fenge=",fenge,"fg=",fg,"fg1=",fg1)
hebing=','.join(fg)#合并
print("hebin=",hebing,"type=",type(hebing))

kaitou=fenge.startswith('aa')#字符头部是否aa
jiewei=fenge.endswith('gg')#字符结尾是否gg
weizhi=fenge.find('dd')#查找字符dd第一个位置
weizhi1=fenge.rfind('dd')#再次找dd字符位置
tongji=fenge.count('dd')#统计dd出现次数
shuzi_abc=fenge.isalnum()#字符是否都是字符和数字
print("kaitou=aa?",kaitou,"jiewei=gg?",jiewei,"weizhi=?",weizhi,"weizhi1=",weizhi1,"tongji'dd'=",tongji,
      "shuziorabc?=",shuzi_abc)

a1= chifan b1= haochide 
a1+b1= chifanhaochide
a1*4= chifanchifanchifanchifan 
b1*4= haochidehaochidehaochidehaochide
a1[0]= c 
b1[1]= a
a1= chifan 
a1[::-1] nafihc
a1[1:4]= hif
a1[::2]= cia
len(a1*4)= 24
fenge= aa,bb,cc,dd,ee,ff,dd,gg fg= ['aa', 'bb', 'cc', 'dd', 'ee', 'ff', 'dd', 'gg'] fg1= ['a', 'a', ',', 'b', 'b', ',', 'c', 'c', ',', 'd', 'd', ',', 'e', 'e', ',', 'f', 'f', ',', 'd', 'd', ',', 'g', 'g']
hebin= aa,bb,cc,dd,ee,ff,dd,gg type= <class 'str'>
kaitou=aa? True jiewei=gg? True weizhi=? 9 weizhi1= 18 tongji'dd'= 2 shuziorabc?= False

#字符的查找和删除
testcha1="this IS red Apple but IS No green---"
#循环找‘-’字符
count=0
for i in testcha1:
    if i=='-':
        count+=1
        print(count)
jieguo1=testcha1.strip('-')#找到-删除
print(testcha1,'\n',jieguo1)

1
2
3
this IS red Apple but IS No green--- 
 this IS red Apple but IS No green

#字符大小写对齐替换
testcha1="this IS red Apple but IS No green---"
shouzimu_daxie=testcha1.capitalize()#首字母第一个大写
allword_firstzimu_daxie=testcha1.title()#所有单词首字母大写
allzimu_daxie=testcha1.upper()#所有字母大写
allzimu_xiaoxie=testcha1.lower()#所有字母小写
daxiao_zhuanhuan=testcha1.swapcase()#大小写字母互转
juzhong=testcha1.center(60)#60字符居中
zuoduiqi=testcha1.ljust(60)#60字符左对齐
youduiqi=testcha1.rjust(60)#60字符右对齐
tihuan=testcha1.replace('IS',"is",2)#替换IS为IS 2次
print("首字母大写=",shouzimu_daxie,"\n所有首字母大写=",allword_firstzimu_daxie,"\n所有字母大写=",allzimu_daxie,
      "\n所有字母小写=",allzimu_xiaoxie,"\n60个字母居中=",juzhong,"\n左对齐=",zuoduiqi,"\n右对齐=",youduiqi,
      "\n替换IS=",tihuan)

#字符大小写对齐替换
testcha1="this IS red Apple but IS No green---"
shouzimu_daxie=testcha1.capitalize()#首字母第一个大写
allword_firstzimu_daxie=testcha1.title()#所有单词首字母大写
allzimu_daxie=testcha1.upper()#所有字母大写
allzimu_xiaoxie=testcha1.lower()#所有字母小写
daxiao_zhuanhuan=testcha1.swapcase()#大小写字母互转
juzhong=testcha1.center(60)#60字符居中
zuoduiqi=testcha1.ljust(60)#60字符左对齐
youduiqi=testcha1.rjust(60)#60字符右对齐
tihuan=testcha1.replace('IS',"is",2)#替换IS为IS 2次
print("首字母大写=",shouzimu_daxie,"\n所有首字母大写=",allword_firstzimu_daxie,"\n所有字母大写=",allzimu_daxie,
      "\n所有字母小写=",allzimu_xiaoxie,"\n60个字母居中=",juzhong,"\n左对齐=",zuoduiqi,"\n右对齐=",youduiqi,
      "\n替换IS=",tihuan)