如何在文本文件中找到某个字符串的行号？

Question

编辑：感谢所有帮助家伙！ 我已经在评论部分找到了我的答案，但我不知道如何将评论标记为已回答！ 谢谢你，Dainius Preimantas 回答我的问题！

我有一个文本文件，想在文本文件中找到某个字符串，然后返回该字符串所在的行号？ 例如：

with open("File.txt", "r+") as f:
    f.find(stringvalue)
    linenumber = #whatever line number value is returned

文本文件（“File.txt”）：

密码银行，jack789

BankEpic,Epic1234

Bank1,Bank123

大师，大师123

Answer 1

尝试这样的事情：

f=open('filename.txt','r')
text=f.read().split('\n')
string_to_find='string'
for line in range(text):
    if string_to_find in text[line]:
        return line

将来，在提问时，请参阅我们的指南，了解如何提出好问题？

Answer 2

substring = "42 is the answer"
filename = "file.txt"
with open(filename, "r") as file:
    line = file.readline()
    i = 1
    flag = False
    while line:
        if substring in line: #Or any other string matching condition
            flag = True
        if flag:
            break
        line = file.readline()
        i += 1
    if flag:
        print(i)
    else:
        print("Line not found")

Answer 3

这 100% 有效 我为你试过了

placeholder = 0

file = open("filename.txt", "r")
all_lines = file.readlines()

while placeholder < len(all_lines):
    each_line = all_lines[placeholder]
    if " yourString " in each_line:
        print("yes in line: " + str(placeholder+1))
        placeholder += 1
    else:
        placeholder += 1