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

Question

每当任务（对于patternStart.finditer(TestString) 中的匹配）未找到匹配项时，我都会尝试打印（未找到匹配项）。我一直坚持这个没有任何成功。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 counterwanted1 = [1]  # Defines the 1-based IDs of the matches you want to displaywanted2 = [2]  # Defines the 1-based IDs of the matches you want to displayfor match in patternStart.finditer(TestString):    cnt += 1    if cnt in wanted1:        out = match.group()    else:        print('match was not found')我已经尝试过了。if match.group() is None:    print('match was not found')if out is None:    print('match was not found')

Answer 1

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')

或者使用单独的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')