《Python核心编程》部分代码习题实践(持续更新)
第三章
3-10 交换异常处理方式
代码:
#makeTextFile.py #!/usr/bin/env python 'makeTextFile.py'
import os
ls = os.linesep #get File name while True:
fname = raw_input("Enter file name: ")
try:
fobj = open(fname,'w')
except IOError, e:
print "File open Failed"
else:
break; #get file contents lines all = []
print "\nEnter lines('.' by itself to quit).\n" #loop until user terminate input while True:
entry = raw_input('> ')
if entry == '.':
break
else:
all.append(entry) #write lines to file with proper line-ending
#fobj = open(fname,'w')
fobj.writelines(['%s%s' % (x,ls) for x in all])
#fobj.write('\n',join(all))
fobj.close()
print "DONE" ###################################### #readTextFile.py #!/usr/bin/env python 'readTextFile.py'
import os #get filename
fname = raw_input('Enter filename: ')
print #attempt to open file for reading if os.path.exists(fname):
fobj = open(fname,'r')
for eachLine in fobj:
print eachLine, fobj.close()
3-11 移除逗号,用strip方法
代码:
#!/usr/bin/env python 'readTextFile.py'
import os #get filename
fname = raw_input('Enter filename: ')
print #attempt to open file for reading if os.path.exists(fname):
fobj = open(fname,'r')
for eachLine in fobj:
print eachLine.strip() #string.strip() fobj.close()
第五章习题:
"chapter 5 's example"
import random def countLevel(grade):
"countLevel: input a grade,output its level"
if grade > 100 or grade < 0:
return 'Grade invalid!'
elif 90 <= grade <= 100:
return 'A'
elif 80 <= grade < 90:
return 'B'
elif 70 <= grade < 80:
return 'C'
elif 60 <= grade < 70:
return 'D'
else:
return 'E' def countAvg(gradelist):
sumi = 0
for i in gradelist:
sumi += i
return float(sumi)/len(gradelist) def matchStr(ka,kb):
len1 = len(ka)
len2 = len(kb)
if len1 != len2:
return False
i = 0
while i < len1:
if ka[i] != kb[i]:
return False
i += 1
return True def moneydiv(money):
"There are 4 kinds of coins,input a num,output the minimum coins used to spell it"
m1 = m5 = m10 = m25 = 0
if money >= 25:
m25 = money/25
money -= m25*25
if money >= 10:
m10 = money/10
money -= m10*10
if money >= 5:
m5 = money/5
money -= m5*5
if money >= 1:
m1 = money
return [m1,m5,m10,m25] def EvalInt3(expression):
"input a expression,output it's consequence,only for int"
length = len(expression)
a = ""
b = ""
op = ""
first = True
tag = 0
for i in range(0,length):
if expression[i] != '+' and expression[i] != '-' and expression[i] != '*' and expression[i] != '/' and expression[i] != '%':
if first:
a += expression[i]
else:
b += expression[i]
else:
if expression[i] == '*' and expression[i-1] == '*':
tag = 6
first = False
else:
if expression[i] == '+':
tag = 1
elif expression[i] == '-':
tag = 2
elif expression[i] == '*':
tag = 3
elif expression[i] == '/':
tag = 4
elif expression[i] == '%':
tag = 5
first = False
a = int(a)
b = int(b)
if tag == 1:
return a+b
elif tag == 2:
return a-b
elif tag == 3:
return a*b
elif tag == 4:
return a/b
elif tag == 5:
return a%b
elif tag == 6:
return a**b def SquareArea(a):
return a*a def CubeVolume(a):
return a*a*a def CircleArea(r):
return 3.14159*r*r def SphereVolume(r):
return 4.0/3.0*3.14159*r*r*r def TempCtoF(c):
return str(9.0/5.0*c + 32) + 'F' def TempFtoC(f):
return str((f-32)*(5.0/9.0)) + 'C' def interest(ist):
dayist = ist/365.0/100.0
return ((1+dayist)**365 - 1.0)*100 def GCD(a,b):
"count gcd of two number"
if b:
return GCD(b,a%b)
else:
return a def RandomGO(N,n):
a = []
for i in range(0,N):
k = random.randrange(0,n)
a.append(k)
b = []
for i in range(0,N):
ind = random.randrange(0,N)
b.append(a[ind])
sorted(b)
return b def displayNumType(num):
print num,'is',
if isinstance(num,(int,long,float,complex)):
print 'a number of type:',type(num).__name__
else:
print 'not a number at all!!'
第六-七章习题:
6-12
#!/usr/bin/env python def findchr(string, char):
i = 0
for ch in string:
if ch == char:
return i
i += 1
return -1 def rfindchr(string, char):
i = len(string)-1
while i >= 0:
if(string[i] == char):
return i
i -= 1
return -1 def subchr(string, origchar, newchar):
i = 0
newstring = ""
for ch in string:
if ch == origchar:
newstring += newchar
continue
newstring += ch
return newstring print rfindchr('whatbeg','')
print rfindchr('wahtbeg','b')
print rfindchr('whahhhaaad','a')
print subchr('whatbeg','w','t')
#!/usr/bin/env python "Chapter 6" def num_to_str():
num_str = raw_input('Enter a number: ') i = 0 num_dic = {'':'zero','':'one','':'two','':'three','':'four','':'five','':'six','':'seven','':'eight','':'nine'}
res = [] while i < len(num_str):
res.append(num_dic[num_str[i]])
i += 1 i = 0
stri = '' while i < len(res)-1:
stri += res[i] + '-'
i += 1 stri += res[i] print stri "Chapter 7" def Exchange_Key_Values(dict1):
dict2 = {}
for key in dict1:
dict2[dict1[key]] = key return dict2
第八章:
# -*- coding: cp936 -*- print '输入起始值: '
num_str1 = raw_input()
num1 = int(num_str1)
print '输入结束值: '
num_str2 = raw_input()
num2 = int(num_str2) print 'DEC BIN OCT HEX ASCII'
print '----------------------------------------' for i in range(num1,num2+1):
print str(i) + ' ' + bin(i) + ' ' + oct(i) + ' ' + hex(i) + ' ' + chr(i)
第九章:
#9-4
f = open('1.txt','r') while True:
for i in range(12):
print f.readline()
a = raw_input('Press any key to continue, "q" to quit: ')
if a == 'q':
break;
else:
continue
#复制文件
print 'Enter the two file name: '
no1 = raw_input('From: ')
no2 = raw_input('To: ') f1 = open(no1,'r')
f2 = open(no2,'w') for eachLine in f1.readlines():
f2.write(eachLine) f1.close()
f2.close() print 'Done!'
#9-18 搜索某个ASCII码对应的字符在文件中出现的次数
name = raw_input('Enter the file name: ')
char_num = raw_input('And the char_num: ')
char_num_int = int(char_num)
char = chr(char_num_int) f = open(name,'r') cnt = 0 for eachLine in f.readlines():
for i in eachLine:
if char == i:
cnt += 1 f.close() print 'Done! COUNT is ' + str(cnt)
第11章:
爬取网页代码第一行和最后一行:
#!/usr/bin/env python from urllib import urlretrieve def firstNonBlank(lines):
for eachLine in lines:
if not eachLine.strip():
continue
else:
return eachLine def firstLast(webpage):
f = open(webpage)
lines = f.readlines()
f.close()
print firstNonBlank(lines)
lines.reverse()
print firstNonBlank(lines) def download(url = 'http://www.codeforces.com',process = firstLast):
try:
retval = urlretrieve(url)[0]
except IOError:
retval = None
if retval:
process(retval) if __name__ == '__main__':
download('http://acm.uestc.edu.cn/#/')
测试函数:
#!/usr/bin/env python def testit(func,*nkwargs,**kwargs):
try:
retval = func(*nkwargs,**kwargs)
result = (True, retval)
except Exception, diag:
result = (False, str(diag))
return result def test():
funcs = (int, long, float)
vals = (1234,12.34,'','12.34')
for eachFunc in funcs:
print '_'*20
for eachVal in vals:
retval = testit(eachFunc,eachVal)
if retval[0]:
print '%s(%s) = ' % (eachFunc.__name__,'eachVal'),retval[1]
else:
print '%s(%s) = FAILED: ' % (eachFunc.__name__,'eachVal'),retval[1] if __name__ == '__main__':
test()
简单GUI例子
from functools import partial
import Tkinter root = Tkinter.Tk()
MyButton = partial(Tkinter.Button,root,fg = 'white',bg = 'blue')
b1 = MyButton(text = 'Button 1')
b2 = MyButton(text = 'Button 2') qb = MyButton(text = 'QUIT',bg = 'red',command=root.quit) b1.pack()
b2.pack() qb.pack(fill = Tkinter.X,expand = True)
root.title('PFAs!')
root.mainloop()
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