When developing the beautiful beauty picture station, the collection used python
4 spaces are recommended for python indentation
if loop
if else
if expression
statement(s)
if 1<2:
print "hello"
elif 'a':
print "world"
else:
print "END"
Run in this format, if the condition is true, run the following program, if not, do not execute else
example:
#!/usr/bin/python
a = int(raw_input("please input a number:"))
if a >= 90:
print 'A'
elif a >= 70:
print 'B'
elif a >= 60:
print 'C'
else:
print 'D'
print 'This is you score!'
while loop
while loop is used in conditional loop
Example 1
#!/usr/bin/python
x = ''
while x != 'q':
print 'hello'
x = raw_input("please input :")
if not x:
break
if x == 'quit'
continue
print 'continue'
else:
print 'world'
Use while loop to iterate through files
Example 2
fd = open('/work/python/1.txt')
while True:
line = fd.readline()
if not line:
break
print line,
fd.close()
The for loop is used in a loop with a number of times
iterate over the list
Example 1
#!/usr/bin/python
for i in range(10):
if i % 2 ==0:
print i,
Example 2: List rewriting
#!/usr/bin/python
print [i for i in range(10) if i % 2 == 0]
Example 3: List rewriting
#!/usr/bin/python
for z in [i for i in range(10) if i % 2 == 0]:
print z
iterate over the dictionary
dic1 = {'a':100, 'b':100, 'c':100, 'd':100}
Example 1
for k in dic1:
print k
Example 2
for k in dic1:
print k dic1[k]
Example 3
for k in dic1:
#, to remove newlines
print "%s-->%s" % (k, dic1[k]),
Example 4
#Use iteritems() and a for loop to iterate over the values in the dictionary
for k, v in dic1.iteritems():
print k, v
Example 5
#Use for loop to write multiplication formula
for i in xrange(1,10):
for k in xrange(1,i+1):
print "%s X %s = %s" % (i, k, i*k),
The else of the for loop exits, and the else content will be executed after the for loop ends.
Example 6
Several syntax usages of #for loop
import sys
import time
for i in xrange(10):
if i == 1:
continue
elif i == 3:
pass
elif i == 5:
break
elif i == 7:
sys.exit()
else:
print i
time.sleep(1)
print "2"
Example 7 Using a for loop to traverse the contents of a file
#!/usr/bin/python
fd = open('/work/python/2.txt')
for line in fd:
print line,
The enumerate() method means enumeration and enumeration in the dictionary