6个实例，8段代码，详解 Python 中的 For 循环

line = '1 2 3 4 10e abc' 
sum  = 0 
invalidStr = "" 
 
print('String of numbers:',line) 
 
for str in line.split(" "): 
  try: 
    sum = sum + eval(str) 
  except: 
    invalidStr = invalidStr + str + ' ' 
 
print('sum:', sum) 
if(invalidStr != ""): 
  print('Invalid strings:',invalidStr) 
else: 
  print('All substrings are valid numbers') 

maxPower = 4 
maxCount = 4 
 
def pwr(num): 
  prod = 1 
  for n in range(1,maxPower+1): 
    prod = prod*num 
    print(num,'to the power',n, 'equals',prod) 
  print('-----------') 
 
for num in range(1,maxCount+1): 
    pwr(num) 

max = 8 
for x in range(1,max+1): 
  for y in range(1,x+1): 
    print(y,'', end='') 
  print()  

x = 'This is a string that contains abc and Abc' 
y = 'abc' 
identical = 0 
casematch = 0 
 
for w in x.split(): 
  if(w == y): 
    identical = identical + 1 
  elif (w.lower() == y.lower()): 
    casematch = casematch + 1 
 
if(identical > 0): 
 print('found identical matches:', identical) 
 
if(casematch > 0): 
 print('found case matches:', casematch) 
 
if(casematch == 0 and identical == 0): 
 print('no matches found') 

import string 
 
wordCount = 0 
str1 = 'this is a string with a set of words in it' 
 
print('Left-justified strings:') 
print('-----------------------') 
for w in str1.split(): 
   print('%-10s' % w) 
   wordCount = wordCount + 1 
   if(wordCount % 2 == 0): 
      print("") 
print("n") 
 
print('Right-justified strings:')  
print('------------------------')  
 
wordCount = 0 
for w in str1.split(): 
   print('%10s' % w) 
   wordCount = wordCount + 1 
   if(wordCount % 2 == 0): 
      print() 

import string 
 
left = 0 
right = 0 
columnWidth = 8 
 
str1 = 'this is a string with a set of words in it and it will be split into a fixed column width' 
strLen = len(str1) 
 
print('Left-justified column:')  
print('----------------------')  
rowCount = int(strLen/columnWidth) 
 
for i in range(0,rowCount): 
   left  = i*columnWidth 
   right = (i+1)*columnWidth-1 
   word  = str1[left:right] 
   print("%-10s" % word) 
 
# check for a 'partial row' 
if(rowCount*columnWidth < strLen): 
   left  = rowCount*columnWidth-1; 
   right = strLen 
   word  = str1[left:right] 
   print("%-10s" % word) 

text1 = 'a b c d' 
text2 = 'a b c e d' 
 
if(text2.find(text1) >= 0): 
  print('text1 is a substring of text2') 
else: 
  print('text1 is not a substring of text2') 
 
subStr = True 
for w in text1.split(): 
  if(text2.find(w) == -1): 
    subStr = False 
    break 
 
if(subStr == True): 
  print('Every word in text1 is a word in text2') 
else: 
  print('Not every word in text1 is a word in text2') 

text = 'abcdef' 
for ch in text: 
   print('char:',ch,'ord value:',ord(ch)) 
print