Examples for string find in Python
Question:
I am trying to find some examples but no luck. Does anyone know of some examples on the net? I would like to know what it returns when it can’t find, and how to specify from start to end, which I guess is going to be 0, -1.
Answers:
I’m not sure what you’re looking for, do you mean find()
?
>>> x = "Hello World"
>>> x.find('World')
6
>>> x.find('Aloha');
-1
you can use str.index
too:
>>> 'sdfasdf'.index('cc')
Traceback (most recent call last):
File "<pyshell#144>", line 1, in <module>
'sdfasdf'.index('cc')
ValueError: substring not found
>>> 'sdfasdf'.index('df')
1
find( sub[, start[, end]])
Return the lowest index in the string where substring sub is found, such that sub is contained in the range [start, end]. Optional arguments start and end are interpreted as in slice notation. Return -1 if sub is not found.
From the docs.
Honestly, this is the sort of situation where I just open up Python on the command line and start messing around:
>>> x = "Dana Larose is playing with find()"
>>> x.find("Dana")
0
>>> x.find("ana")
1
>>> x.find("La")
5
>>> x.find("La", 6)
-1
Python’s interpreter makes this sort of experimentation easy. (Same goes for other languages with a similar interpreter)
From the documentation:
str.find(sub[, start[, end]])
Return the lowest index in the string where substring sub is found within the slice s[start:end]
. Optional arguments start and end are interpreted as in slice notation. Return -1
if sub is not found.
So, some examples:
>>> my_str = 'abcdefioshgoihgs sijsiojs '
>>> my_str.find('a')
0
>>> my_str.find('g')
10
>>> my_str.find('s', 11)
15
>>> my_str.find('s', 15)
15
>>> my_str.find('s', 16)
17
>>> my_str.find('s', 11, 14)
-1
If you want to search for the last instance of a string in a text, you can run rfind.
Example:
s="Hello"
print s.rfind('l')
output: 3
*no import needed
Complete syntax:
stringEx.rfind(substr, beg=0, end=len(stringEx))
Try this:
with open(file_dmp_path, 'rb') as file:
fsize = bsize = os.path.getsize(file_dmp_path)
word_len = len(SEARCH_WORD)
while True:
p = file.read(bsize).find(SEARCH_WORD)
if p > -1:
pos_dec = file.tell() - (bsize - p)
file.seek(pos_dec + word_len)
bsize = fsize - file.tell()
if file.tell() < fsize:
seek = file.tell() - word_len + 1
file.seek(seek)
else:
break
if x is a string and you search for y which also a string their is two cases :
case 1: y is exist in x so x.find(y) = the index (the position) of the y in x .
case 2: y is not exist so x.find (y) = -1 this mean y is not found in x.
Try
myString = 'abcabc'
myString.find('a')
This will give you the index!!!
I am trying to find some examples but no luck. Does anyone know of some examples on the net? I would like to know what it returns when it can’t find, and how to specify from start to end, which I guess is going to be 0, -1.
I’m not sure what you’re looking for, do you mean find()
?
>>> x = "Hello World"
>>> x.find('World')
6
>>> x.find('Aloha');
-1
you can use str.index
too:
>>> 'sdfasdf'.index('cc')
Traceback (most recent call last):
File "<pyshell#144>", line 1, in <module>
'sdfasdf'.index('cc')
ValueError: substring not found
>>> 'sdfasdf'.index('df')
1
find( sub[, start[, end]])
Return the lowest index in the string where substring sub is found, such that sub is contained in the range [start, end]. Optional arguments start and end are interpreted as in slice notation. Return -1 if sub is not found.
From the docs.
Honestly, this is the sort of situation where I just open up Python on the command line and start messing around:
>>> x = "Dana Larose is playing with find()"
>>> x.find("Dana")
0
>>> x.find("ana")
1
>>> x.find("La")
5
>>> x.find("La", 6)
-1
Python’s interpreter makes this sort of experimentation easy. (Same goes for other languages with a similar interpreter)
From the documentation:
str.find(sub[, start[, end]])
Return the lowest index in the string where substring sub is found within the slice
s[start:end]
. Optional arguments start and end are interpreted as in slice notation. Return-1
if sub is not found.
So, some examples:
>>> my_str = 'abcdefioshgoihgs sijsiojs '
>>> my_str.find('a')
0
>>> my_str.find('g')
10
>>> my_str.find('s', 11)
15
>>> my_str.find('s', 15)
15
>>> my_str.find('s', 16)
17
>>> my_str.find('s', 11, 14)
-1
If you want to search for the last instance of a string in a text, you can run rfind.
Example:
s="Hello"
print s.rfind('l')
output: 3
*no import needed
Complete syntax:
stringEx.rfind(substr, beg=0, end=len(stringEx))
Try this:
with open(file_dmp_path, 'rb') as file:
fsize = bsize = os.path.getsize(file_dmp_path)
word_len = len(SEARCH_WORD)
while True:
p = file.read(bsize).find(SEARCH_WORD)
if p > -1:
pos_dec = file.tell() - (bsize - p)
file.seek(pos_dec + word_len)
bsize = fsize - file.tell()
if file.tell() < fsize:
seek = file.tell() - word_len + 1
file.seek(seek)
else:
break
if x is a string and you search for y which also a string their is two cases :
case 1: y is exist in x so x.find(y) = the index (the position) of the y in x .
case 2: y is not exist so x.find (y) = -1 this mean y is not found in x.
Try
myString = 'abcabc'
myString.find('a')
This will give you the index!!!