Python program to count upper and lower case characters without using inbuilt functions

Given a string that contains both upper and lower case characters in it. The task is to count a number of upper and lower case characters in it.

 Examples :

Input : Introduction to Python
Output : Lower Case characters : 18 
         Upper case characters : 2

Input :  Welcome to GeeksforGeeks
Output : Lower Case characters : 19  
         Upper case characters: 3

Method 1: Using the built-in methods

Python3

Str="GeeksForGeeks"
lower=0
upper=0
for i in Str:
      if(i.islower()):
            lower+=1
      else:
            upper+=1
print("The number of lowercase characters is:",lower)
print("The number of uppercase characters is:",upper)

Output

The number of lowercase characters is: 10
The number of uppercase characters is: 3

Time Complexity: O(n)
Auxiliary Space: O(1)

Explanation:

Here we are simply using the built-in method islower() and checking for lower case characters and counting them and in the else condition we are counting the number of upper case characters provided that the string only consists of alphabets.

 Method 2: Using the ascii values, Naive Method

Python3

# Python3 program to count upper and
# lower case characters without using
# inbuilt functions
def upperlower(string):

    upper = 0
    lower = 0

    for i in range(len(string)):

        # For lower letters
        if (ord(string[i]) >= 97 and
            ord(string[i]) <= 122):
            lower += 1

        # For upper letters
        elif (ord(string[i]) >= 65 and
            ord(string[i]) <= 90):
            upper += 1

    print('Lower case characters = %s' %lower,
        'Upper case characters = %s' %upper)

# Driver Code
string = 'GeeksforGeeks is a portal for Geeks'
upperlower(string)

Output

Lower case characters = 27 Upper case characters = 3

Time Complexity: O(n)
Auxiliary Space: O(1)

Explanation:

Here we are using the ord() method to get the ascii value of that particular character and then calculating it in the particular range.

Method 3: Calculating the characters within the given range of ascii code

Python3

s = "The Geek King"
l,u = 0,0
for i in s:
    if (i>='a'and i<='z'):

        # counting lower case
        l=l+1
    if (i>='A'and i<='Z'):

        #counting upper case
        u=u+1

print('Lower case characters: ',l)
print('Upper case characters: ',u)

Output

Lower case characters:  8
Upper case characters:  3

Time Complexity: O(n)
Auxiliary Space: O(1)

Explanation:

Here we are iterating through the string and calculating upper and lower case characters using the ascii code range.

Method 4: Using ‘in’ keyword

Python3

# Python3 program to count upper and
# lower case characters without using
# inbuilt functions
string = 'GeeksforGeeks is a portal for Geeks'
upper = 0
lower = 0
up="ABCDEFGHIJKLMNOPQRSTUVWXYZ"
lo="abcdefghijklmnopqrstuvwxyz"
for i in string:
    if i in up:
        upper+=1
    elif i in lo:
        lower+=1
print('Lower case characters = %s' %lower)
print('Upper case characters = %s' %upper)

Output

Lower case characters = 27
Upper case characters = 3

Time Complexity: O(n)
Auxiliary Space: O(1)

Explanation:

Here we have taken all the upper and lower case characters in separate strings and then count how many characters are present in individual strings.

Method #5 : Using operator.countOf() method

Python3

import operator as op
Str = "GeeksForGeeks"
lower = "abcdefghijklmnopqrstuvwxyz"
l = 0
u = 0
for i in Str:
    if op.countOf(lower, i) > 0:
        l += 1
    else:
        u += 1
print("The number of lowercase characters is:", l)
print("The number of uppercase characters is:", u)

Output

The number of lowercase characters is: 10
The number of uppercase characters is: 3

Time Complexity: O(n)

Space Complexity: O(1)