我想检查一个字符串是否在文本文件中。如果是，执行x。如果不是，执行y。然而，由于某种原因，这段代码总是返回True。有人能看出哪里不对吗?
def check():
datafile = file('example.txt')
found = False
for line in datafile:
if blabla in line:
found = True
break
check()
if True:
print "true"
else:
print "false"
当前回答
两个问题:
你的函数没有返回任何东西;不显式返回任何内容的函数返回None(这是假的) True始终为True—您不是在检查函数的结果
.
def check(fname, txt):
with open(fname) as dataf:
return any(txt in line for line in dataf)
if check('example.txt', 'blabla'):
print "true"
else:
print "false"
其他回答
两个问题:
你的函数没有返回任何东西;不显式返回任何内容的函数返回None(这是假的) True始终为True—您不是在检查函数的结果
.
def check(fname, txt):
with open(fname) as dataf:
return any(txt in line for line in dataf)
if check('example.txt', 'blabla'):
print "true"
else:
print "false"
这是另一个。获取绝对文件路径和给定字符串并将其传递给word_find()，在enumerate()方法中对给定文件使用readlines()方法，该方法在逐行遍历时给出可迭代计数，最终为您提供具有匹配字符串的行，加上给定的行号。欢呼。
def word_find(file, word):
with open(file, 'r') as target_file:
for num, line in enumerate(target_file.readlines(), 1):
if str(word) in line:
print(f'<Line {num}> {line}')
else:
print(f'> {word} not found.')
if __name__ == '__main__':
file_to_process = '/path/to/file'
string_to_find = input()
word_find(file_to_process, string_to_find)
found = False
def check():
datafile = file('example.txt')
for line in datafile:
if blabla in line:
found = True
break
return found
if check():
print "true"
else:
print "false"
found = False
def check():
datafile = file('example.txt')
for line in datafile:
if "blabla" in line:
found = True
break
return found
if check():
print "found"
else:
print "not found"
check函数应该返回找到的布尔值，并使用它来确定要打印的内容。
def check():
datafile = file('example.txt')
found = False
for line in datafile:
if blabla in line:
found = True
break
return found
found = check()
if found:
print "true"
else:
print "false"
第二部分也可以压缩为:
if check():
print "true"
else:
print "false"
