Python – ‘str’ object does not support item assignment

pythonstring

I would like to read some characters from a string s1 and put it into another string s2.

However, assigning to s2[j] gives an error:

s2[j] = s1[i]

# TypeError: 'str' object does not support item assignment

In C, this works:

int i = j = 0;
while (s1[i] != '\0')
    s2[j++] = s1[i++];

My attempt in Python:

s1 = "Hello World"
s2 = ""
j = 0

for i in range(len(s1)):
    s2[j] = s1[i]
    j = j + 1

Best Answer

The other answers are correct, but you can, of course, do something like:

>>> str1 = "mystring"
>>> list1 = list(str1)
>>> list1[5] = 'u'
>>> str1 = ''.join(list1)
>>> print(str1)
mystrung
>>> type(str1)
<type 'str'>

if you really want to.

Related Solutions

Python – TypeError: ‘str’ object does not support item assignment (Python)

You cannot modify the contents of a string, you can only create a new string with the changes. So instead of the function above you'd want something like this

def loop(input):
    for index in range(0, len(input)-3):              #column length
        output = input[:index] + '***' + input[index+4:]
        print output

Python – TypeError: a bytes-like object is required, not ‘str’ when writing to a file in Python3

You opened the file in binary mode:

with open(fname, 'rb') as f:

This means that all data read from the file is returned as bytes objects, not str. You cannot then use a string in a containment test:

if 'some-pattern' in tmp: continue

You'd have to use a bytes object to test against tmp instead:

if b'some-pattern' in tmp: continue

or open the file as a textfile instead by replacing the 'rb' mode with 'r'.

Best Answer

Related Solutions

Python – TypeError: ‘str’ object does not support item assignment (Python)

Python – TypeError: a bytes-like object is required, not ‘str’ when writing to a file in Python3

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