我想在 .txt 文件中搜索某個字符 (X)，如果存在，則執行某個操作。不幸的是這段代碼不起作用：file = "test.txt"file = open(file, "r") lines = file.readlines()# char in the listif "X" in lines: print('X is present in the list')# char not in the listif "X" not in lines: print('X is not present in the list')測試.txt 文件：XX X XXX X XXXXXXX XX X XX有什么想法嗎？PS：即使將“X”更改為“X”也不起作用。
3 回答
MM們
TA貢獻1886條經驗 獲得超2個贊
如果您需要知道X出現的行號：
target = 'X'
counter = 0
with open('testing.txt') as f:
for i, line in enumerate(f):
if target in line:
counter += 1
print('target is present in line {}'.format(
i+1))
print('target appears in {} lines'.format(counter))
如果您還需要知道X出現的列號：
target = 'X'
counter = 0
with open('testing.txt') as f:
for i, line in enumerate(f):
for j, char in enumerate(line):
if target == char:
counter += 1
print('target is present in line {} at column {}'.format(
i+1, j+1))
print('target appears {} times'.format(counter))
一些澄清：
with ... open完成后自動關閉文件，因此您無需記住顯式關閉它for i, line in enumerate(f):逐行迭代，而不將它們一次性全部加載到內存中。
PIPIONE
TA貢獻1829條經驗 獲得超9個贊
由于readlines()是一個列表，您需要迭代并簽入行。也許您可以用于for else此目的：
file = "testing.txt"
file = open(file, "r")
lines = file.readlines()
# char in the list
for line in lines:
if "X" in line:
print('X is present in the list')
break
else:
print('X is not present in the list')
它迭代每一行，如果任何行有字符，則break僅else在任何行中都找不到字符時才運行。
更新
如果你想計數，那么你可以簡單地在循環中增加計數器，一旦循環完成檢查計數器：
file = "testing.txt"
file = open(file, "r")
lines = file.readlines()
# char in the list
counter = 0
for line in lines:
if "X" in line:
counter += 1 # < -- count
if counter: # check
print('X is present in the list')
else:
print('X is not present in the list')
ibeautiful
TA貢獻1993條經驗 獲得超6個贊
正如您所要求的，我將輸出一個包含 item 的列表Yes, there are 3 X's。
我有我的dataf.txt文件：
XXX X XX X XX
X ASD X F FFFF XX
D X XXX X EFX
A F G
將數據讀入文件并計算 X 的數量（注意：我使用了列表理解 hack！）
with open('dataf.txt','r') as fl:
data = fl.readlines()
a = ['Yes, there are '+str(i.count('X')) + " X's" if 'X' in i else "No X's" for i in data]
print(a)
輸出：
["Yes, there are 9 X's", "Yes, there are 4 X's", "Yes, there are 6 X's", "No X's"]
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