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python - 每当任务（patternstart.finditer 中的匹配）返回 None 时，我如何创建操作？

问题描述

每当任务（对于 patternStart.finditer(TestString) 中的匹配项）找不到匹配项时，我都会尝试打印（未找到匹配项）。我一直坚持这一点，没有任何成功。任何意见，将不胜感激。

字符串 'jeke' 故意不包含数字，因此找不到匹配项。

TestString = 'jeke'
patternStart = re.compile(r'\d')


cnt = 0  # Initialize the counter
wanted1 = [1]  # Defines the 1-based IDs of the matches you want to display
wanted2 = [2]  # Defines the 1-based IDs of the matches you want to display


for match in patternStart.finditer(TestString):
    cnt += 1
    if cnt in wanted1:
        out = match.group()

    else:
        print('match was not found')

我尝试过的尝试。


if match.group() is None:
    print('match was not found')

if out is None:
    print('match was not found')

标签： pythonregex

解决方案

您可以使用cnt来确定是否找到任何匹配项：

for match in patternStart.finditer(TestString):
    cnt += 1
    if cnt in wanted1:
        out = match.group()
if cnt == 0:
    print('match was not found')

或使用单独的found_match变量：

found_match = False
for match in patternStart.finditer(TestString):
    found_match = True
    cnt += 1
    if cnt in wanted1:
        out = match.group()
if not found_match:
    print('match was not found')

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