替换字符串中的奇数和偶数索引字符

Question

How can I replace even and odd-indexed letters in my strings? I'd like to replace odd-indexed characters with uppercased letters and even-indexed characters with lowercased ones.

x=input("Enter String: ")

How can I modify the inputted string?

Answer 1

This sounds a little like a "do my homework for me" post, but I'll help you out, as I need the training myself.

You can do this by breaking down the problem. (As I am quite new with python syntax, I'm gonna assume that the user has already given an input to string x)

1. Make a loop, or otherwise iterate through the characters of your string
2. Make sure you have an index number for each character, which increments for each one
3. Check if the number is even, by using modulus of 2 ( %2 ). This returns the remainder of a number when divided by 2. In the case of even numbers, that will be 0.
4. If %2 == 0 set letter to lower case, else set letter to upper case.
5. append letter to new String, which you defined before the loop. You cannot directly alter a single character in a String, because they are immutable. This means that you cannot change the String itself, but you can assign a new String to the variable.
6. Done. Print and see if it worked.

Code:

x = "seMi Long StRing WiTH COMPLetely RaNDOM CasINg"
result_string = ""
index = 0;
for c in x:
    if(index%2 == 0):
        result_string += c.lower()
    else:
        result_string += c.upper()
    index+=1

print(result_string)

Answer 2

s=input()
l=[]
s=s.lower()
l=[i.upper() if s.index(i)%2==0 else i for i in s ]
print("".join(l))

Answer 3

def myfunc(string):
    result=''
    for x in range(len(string)):
        if x%2==0:
            result=result+string[x].upper() 
        else:
            result=result+string[x].lower()
    return result

The above is a function for the question you asked.

A non-function for loop might be easier to grasp right now (like you I am very new to Python as well. So for me it was easier to understand the for loop before I got into functions. Look at my next post for the same.

Answer 4

x = 'myname'
for item in range(len(x)):
    if item%2==0:
       print(x[item].upper())
    else:
       print(x[item].lower())

this is the for loop i was referring to. but the thing with this line of code is that it is specific to the value you have assigned to the variable x where as the function i provided above can take any string value without us having to repeat the code each time.