Replace a string in a specific index in a line using python

Question

I'm working on a python project and I want to replace a specific word in a line in a file (text.txt) with another string. Like I have this line <string name="AppName">old string</string> And I want to replace the old string by a variable. That's why I don't want to use replace('old string','new string') I want to replace it depending on an index. Any help is highly appreciated. To be more clear I want to replace whatever is between the first '>' and the second '<' with the new string

Because this word will be changed every time by another string so I won't always have that word Google — beatfloraminederecho
– beatfloraminederecho, Commented May 26, 2022 at 9:58
Please update your question with some more examples which don't have that word Google. — quamrana
– quamrana, Commented May 26, 2022 at 10:00
Maybe what you're trying to do is replace whatever is between the first '>' and the second '<'. Is that it? — jackal
– jackal, Commented May 26, 2022 at 10:10
@dinarobert I have edited my original answer. Maybe that works for you — jackal
– jackal, Commented May 26, 2022 at 10:17

jackal · Accepted Answer · 2022-05-26 10:16:51Z

2

This is will replace whatever is between the first '>' and the second '<' with the given string:

s = '<string name="AppName">old string</string>'

def replace(s, new):
    if (i := s.find('>')) >= 0:
        if (j := s[i:].find('<')) >= 0:
            s = s[:i+1] + new + s[j+i:]
    return s

print(replace(s, 'Google'))

Output:

<string name="AppName">Google</string>

Note:

This would be more typically dealt with using RE

edited May 26, 2022 at 10:16

answered May 26, 2022 at 10:07

jackal

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2 Comments

beatfloraminederecho Over a year ago

Thank you so much. What if this line exist in another file "text.txt" how can I use this function to replace it

jackal Over a year ago

@dinarobert I suggest you ask another question. There's nothing in your original question that mentions any kind of file handling

Moonar · Accepted Answer · 2022-05-26 10:25:15Z

Use regex replace

from re import sub

string = "<string name='AppName'>Google</string>"
# anything between the >< will be converted to new_var_string
replace_string = sub(r'>\w+<', f'>{new_var_string}<', string)

example 1:

from re import sub

string = "<string name='AppName'>Google</string>"
# anything between the >< will be converted to new_var_string
new_var_string = 'youtube'
replace_string = sub(r'>\w+<', f'>{new_var_string}<', string)
print(replace_string)

output:

<string name='AppName'>youtube</string>

example 2:

from re import sub

string = "<string name='AppName'>Goo1231gl125125e</string>"
# anything between the >< will be converted to new_var_string
new_var_string = 'youtube'
replace_string = sub(r'>\w+<', f'>{new_var_string}<', string)
print(replace_string)

output:

<string name='AppName'>youtube</string>

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