從Python中的文件中讀取int時出錯

Question

如果一行中有多個整數，如何將該行轉換爲整數。 （在完成行可能是「2 4」和完成= int（行）的原因和錯誤。

另外，我怎樣才能訪問特定元素的轉換在for循環底部。名單，但我需要比較特定元素

with open(r'C:\Users\Andrew\Documents\College\Theory of Computation\dfa19btest.txt', 'r') as f: 
    for i, line in enumerate(f): 
    if i == 0: 
     language = line 
     print("Language =", language) 
    if i == 1: 
     numstates = int(line) 
     print ("Number of states =", numstates) 
    if i == 2: 
     start = int(line) 
     print ("Start =", start) 
    #if i == 3: 
     #finish = int(line) 
     #print ("Finish =", finish) 
    if i >= 4: 
     transitions.append(line) 
     print ("Transitions = ", transitions[i -4]) 

for x in range(numstates-1, -1, -1): 
    print(transitions[x]) 
    # string is in 4 a 2 b 3 format 
    # if [0] == [3] then answer insert [2]* into answer array 
    # if [2] and [4] are followed by same number insert [2]|[4] 

Answer 1

來解析字符串爲整數使用：int

的爲例：

str_var = '123' 
int_var = int(str_var) # int_var now have the interger value 123 

Answer 2

您需要如果您的任何輸入無效，即非整數，則決定應該發生什麼。以下是Python2的簡化示例。注意try/except子句。

with open(r'C:\Users\Andrew\Documents\College\Theory of Computation\dfa19btest.txt', 'r') as f: 
    for i, line in enumerate(f): 
     if i == 0: 
      language = line 
      print("Language =", language) 
     try: 
      if i == 1: 
       numstates = int(line) 
       transitions = np.array(numstates) 
       print ("Number of states =", numstates) 
      if i == 2: 
       start = int(line) 
       print ("Start =", start) 
      if i == 3: 
       finish = int(line) 
       print ("Finish =", finish) 
     except ValueError: 
      print "Invalid int (%s) on line: %d" % (line, i) # use print() for Python3 
      break 

Answer 3

對於線路上的多個整數，該str.split（）函數將是有益的：http://docs.python.org/2/library/stdtypes.html#str.split

a = "1 2 3 4" 
print a.split() -> ["1", "2", "3", "4"] 

你的問題的到底是unclear--什麼是你想用做特定元素？