In this article, we will learn how to convert uppercase characters to lowercase. And also how to check if the string is in lowercase or not.
Python lower() Function
In Python, a built-in function lower() is available that converts uppercase string into lowercase string and returns it.
In laymen language this method converts all the uppercase character present in string in lowercase character, if there is no uppercase character present in the given string it will return the original string.
Syntax
string.lower()
Parameters
Does not take any parameters
Returns
Returns a lowercase string, if no lower case character present it return input string
Example
# Python code to explain lower() function
# Initialize a string with all uppercase characters
str1 = 'STECHIES.COM'
print(str1.lower())
# Initialize a string with uppercase & lowercase characters
str1 = 'StecHies.com'
print(str1.lower())
Output
stechies.com
stechies.com
Explanation
In the above code, we initialized 2 strings with 2 different values. The first variable str1 holds a string in all uppercase characters. Whereas the second variable str2 holds a string with the only first character in uppercase. When we applied lower() function in both the variables. It converted the whole of str1 to lowercase. And only the first character of str2 to lowercase as rest of the string was already in lowercase. Thus we got the shown output.
Use of lower() Function in Application
Example
# Python program to compare two string using lower() function
# Initialize strings to compare
str1 = 'STECHIES'
str2 = 'SteChies'
# Compare string without using lower() function
if(str1 == str2):
print(str1,'and ',str2,' are same')
else:
print(str1,'and ',str2,' are not same')
# Compare string with lower() function
if(str1.lower() == str2.lower()):
print(str1,'and ',str2,' are same')
else:
print(str1,'and ',str2,' are not same')
Output
STECHIES and SteChies are not same
STECHIES and SteChies are same
Explanation
In the above example, we used if-else condition to check if the string are same or not. The first if-else condition gives the output “STECHIES and SteChies are not same”. This is because python is a case sensitive programming language so it treats capital “S” and small ‘s’ as two different characters.
In the second if-else condition we used lower() function to convert uppercase characters to lowercase. After using this function both of our string becomes same. Thud we got the output as “STECHIES and SteChies are same”
islower() function
In python islower() is a build-in function, this function checks whether all the characters present in a string is lowercase or not.
Syntax
string.islower()
Parameters
Does not take any parameters
Returns
- True: if all characters are lowercase
- False: if one or more characters are uppercase
Example
# Python program to check all characters in string is lowercase
# Initialize strings
str1 = 'STECHIES'
str2 = 'SteChies'
str3 = 'stechies'
# Check if strings are in lowercase or not
print('String 1 STECHIES lower: ', str1.islower())
print('String 2 SteChies lower: ', str2.islower())
print('String 3 stechies lower: ', str3.islower())
Output
String 1 STECHIES lower: False
String 2 SteChies lower: False
String 3 stechies lower: True
Explanation
In the above example, we used a built-in function islower() to check whether the given string is in lowercase or not. If the whole of the string is in lower case it returns ‘True’ else it returns ‘false’.
Conclusion
To convert whole of the string into lowercase we use a built-in function lower(). This function converts every character in a string to lowercase. If the string is already in lowercase then the original string is returned. To check whether the string is in lowercase or not we have a built-in function islower(). This function returns the boolean value Ii.e either true or false.