Python String Handling Functions

Question

Is there a specific function that returns true if characters in the string are special characters (ex: #. @. $)? Like, the isalpha() function returns true if all the characters in a string are letters.

I have to create a program where I need to ask a user for a string and then my program must print the length of the string, the number of letters, the number of digits and the number of characters that are not letters.

counter = 0
num = 0
extra = 0
wrd = raw_input("Please enter a short sentence.")
for i in wrd:
 if i.isalpha():
 counter = counter + 1
print "You have " + str(counter) +" letters in your sentence."
for n in wrd:
 if n.isnumeric():
 num = num + 1
print "You have " + str(num) + " number(s) in your sentence"
for l in wrd:
 extra = extra + 1
print "You have " + str(extra) + " characters that are not letters or numbers."

I got the first two parts figured out albeit I'm stuck on the last...I know its easier to just create one while loop but since I already started, I want to stick with three four loops.

• TigerhawkT3: Why not len(wrd) - counter - num?

Answer 1

You don't need another function. Since you've already counted the other characters, subtract them from the total:

print "You have", len(wrd) - counter - num, "characters that are not letters or numbers."

Answer 2

Is there a specific function that returns true if characters in the string are special characters (ex: #. @. $)? Like, the isalpha() function returns true if all the characters in a string are letters.

No, but its pretty easy to create your own:

import string
def has_special_chars(s):
 return any(c in s for c in string.punctuation)

Test:

>>> has_special_chars("ab@tjhjf$dujhf&")
True
>>> has_special_chars("abtjhjfdujhf")
False
>>> 

In your case, you would use it like:

for l in wrd:
 if has_special_chars(l)
 extra=extra+1

---

But as @TigerHawkT3 has already beat me to saying, you should simply use len(wrd) - counter - num instead. Its the most canonical and obvious way.

Answer 3

Just to log a generic answer that will apply beyond this context -

import string
def num_special_char(word):
 count=0
 for i in word:
 if i in string.punctuation:
 count+=1
 return count
print "You have " + str(num_special_char('Vi$vek!')) + " characters that are not letters or numbers."

Output

You have 2 characters that are not letters or numbers.

Answer 4

Use one for loop with if, elif and else:

sentence = raw_input("Please enter a short sentence.")
alpha = num = extra = 0
for character in sentence:
 if character.isspace():
 pass
 elif character.isalpha():
 alpha += 1
 elif character.isnumeric():
 num += 1
 else:
 extra += 1
print "You have {} letters in your sentence.".format(alpha)
print "You have {} number(s) in your sentence".format(num)
print "You have {} characters that are not letters or numbers.".format(extra)