《Python核心编程(第二版)-习题答案》.pdf
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Chun_AppA.fm Page 1011 Wednesday, August 23, 2006 5:19 PM
Answers to Selected Exercises
Chapter 2
5. Loops and numbers
a)
i = 0
while i 11:
i += 1
b)
for i in range(11):
pass
6. Conditionals
n = int(raw_input(enter a number: ))
if n 0:
print negative
elif n 0:
print positive
else:
print zero
1011
Chun_AppA.fm Page 1012 Wednesday, August 23, 2006 5:19 PM
1012 Appendix A
7. Loops and strings
s = raw_input(enter a string: )
for eachChar in s:
print eachChar # (does not print index)
or
for i in range(len(s)):
print i, s[i]
or
i = 0
slen = len(s)
while i slen:
print i, s[i]
or
for i, x in enumerate(s):
print i, x
8. Loops and operators
subtot = 0
for i in range(5):
subtot += int(raw_input(enter a number: ))
print subtot
or
# uses sum() BIF and generator expressions
print sum(int(raw_input(enter a number: )) for i in range(5))
Ch
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