Python || Using If Statements & String Variables

May 29, 2013 admin No comments

As previously mentioned, you can use “int” and “float” to represent numbers, but what if you want to store letters? Strings help you do that.

==== SINGLE CHAR ====

This example will demonstrate a simple program using strings, which checks to see if the user entered the correctly predefined letter.





		
		
			#1 - Guess a letter
			
Python
			
			# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  char.py
#    Description: Demonstrates using char variables
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
    letter = '' # this holds the individual character

    # get data from user
    userInput = input("Please try to guess the letter I am thinking of: ")

    # we only want to check the first character in the string,
    # so we get the letter at index zero and save it into its
    # own variable
    letter = userInput[0]

    # use an if statement to check equality.
    if ((letter == 'a') or (letter == 'A')):
        print("\nYou have guessed correctly!")
    else:
        print("\nSorry, that was not the correct letter I was thinking of..")

if __name__ == "__main__":
    main()
# http://programmingnotes.org/
			
				
					
				
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						# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  char.py
#    Description: Demonstrates using char variables
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
    letter = '' # this holds the individual character
 
    # get data from user
    userInput = input("Please try to guess the letter I am thinking of: ")
 
    # we only want to check the first character in the string,
    # so we get the letter at index zero and save it into its
    # own variable
    letter = userInput[0]
 
    # use an if statement to check equality.
    if ((letter == 'a') or (letter == 'A')):
        print("\nYou have guessed correctly!")
    else:
        print("\nSorry, that was not the correct letter I was thinking of..")
 
if __name__ == "__main__":
    main()
# http://programmingnotes.org/

Notice in line 11 I declare the string data type, naming it “userInput.” I also initialized it as an empty variable. In line 23 I used an “If/Else Statement” to determine if the user entered value matches the predefined letter within the program. I also used the “OR” operator in line 23 to determine if the letter the user entered into the program was lower or uppercase. Try compiling the program simply using this
if (letter == 'a') as your if statement, and notice the difference.

The resulting code should give this as output

Please try to guess the letter I am thinking of: A You have guessed correctly!

==== CHECK IF LETTER IS UPPER CASE ====

This example is similar to the previous one, and will check if a user entered letter is uppercase.





		
		
			#2 - Is Input Uppercase?
			
Python
			
			# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  uppercase.py
#    Description: Demonstrates checking if a char variable is uppercase
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
    letter = '' # this holds the individual character

    # get data from user
    userInput = input("Please enter an UPPERCASE letter: ")

    # get the 1st character in the string
    letter = userInput[0]

    # check to see if entered data falls between uppercase values
    if ((letter >= 'A') and (letter <= 'Z')):
        print("\n'%c' is an is an uppercase letter!" % (letter))
    else:
        print("\nSorry, '%c' is not an uppercase letter.." % (letter))

if __name__ == "__main__":
    main()
# http://programmingnotes.org/
			
				
					
				
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						# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  uppercase.py
#    Description: Demonstrates checking if a char variable is uppercase
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
    letter = '' # this holds the individual character
 
    # get data from user
    userInput = input("Please enter an UPPERCASE letter: ")
 
    # get the 1st character in the string
    letter = userInput[0]
 
    # check to see if entered data falls between uppercase values
    if ((letter >= 'A') and (letter <= 'Z')):
        print("\n'%c' is an is an uppercase letter!" % (letter))
    else:
        print("\nSorry, '%c' is not an uppercase letter.." % (letter))
 
if __name__ == "__main__":
    main()
# http://programmingnotes.org/

Notice in line 21, an If statement was used, which checks to see if the user entered data falls between letter A and letter Z. We did that by using the “AND” operator. So that IF statement is basically saying (in plain english)

IF ('letter' is equal to or greater than 'A') AND ('letter' is equal to or less than 'Z')
THEN it is an uppercase letter

The resulting code should give this as output

Please enter an UPPERCASE letter: g Sorry, 'g' is not an uppercase letter..

==== CHECK IF LETTER IS A VOWEL ====

This example will utilize more if statements, checking to see if the user entered letter is a vowel or not. This will be very similar to the previous example, utilizing the OR operator once again.





		
		
			#3 - Is Input a Vowel?
			
Python
			
			# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  vowel.py
#    Description: Demonstrates checking if a char variable is a vowel
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
    letter = '' # this holds the individual character

    # get data from user
    userInput = input("Please enter a vowel: ")

    # get the 1st character in the string
    letter = userInput[0]

    # check to see if entered data is A,E,I,O,U,Y
    if ((letter == 'a')or(letter == 'A')or(letter == 'e')or
        (letter == 'E')or(letter == 'i')or(letter == 'I')or
        (letter == 'o')or(letter == 'O')or(letter == 'u')or
        (letter == 'U')or(letter == 'y')or(letter == 'Y')):
        print("\nCorrect, '%c' is a vowel!" % (letter))
    else:
        print("\nSorry, '%c' is not a vowel.." % (letter))

if __name__ == "__main__":
    main()
# http://programmingnotes.org/
			
				
					
				
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						# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  vowel.py
#    Description: Demonstrates checking if a char variable is a vowel
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
    letter = '' # this holds the individual character
 
    # get data from user
    userInput = input("Please enter a vowel: ")
 
    # get the 1st character in the string
    letter = userInput[0]
 
    # check to see if entered data is A,E,I,O,U,Y
    if ((letter == 'a')or(letter == 'A')or(letter == 'e')or
        (letter == 'E')or(letter == 'i')or(letter == 'I')or
        (letter == 'o')or(letter == 'O')or(letter == 'u')or
        (letter == 'U')or(letter == 'y')or(letter == 'Y')):
        print("\nCorrect, '%c' is a vowel!" % (letter))
    else:
        print("\nSorry, '%c' is not a vowel.." % (letter))
 
if __name__ == "__main__":
    main()
# http://programmingnotes.org/

This program should be very straight forward, and its basically checking to see if the user entered data is the letter A, E, I, O, U or Y.

The resulting code should give the following output

Please enter a vowel: K Sorry, 'K' is not a vowel..

==== HELLO WORLD v2 ====

This last example will demonstrate using the string data type to print the line “Hello World!” to the screen.





		
		
			#4 - Hello World - String Version
			
Python
			
			# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  string.py
#    Description: Demonstrates using string variables
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string

    # get data from user
    userInput = input("Please enter a sentence: ")

    # display string
    print("\nYou Entered: '%s'" % (userInput))

if __name__ == "__main__":
    main()
# http://programmingnotes.org/
			
				
					
				
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						# =============================================================================
#    Author: Kenneth Perkins
#    Date:   May 29, 2013
#    Updated: Feb 16, 2021
#    Taken From: http://programmingnotes.org/
#    File:  string.py
#    Description: Demonstrates using string variables
# =============================================================================
def main():
    # declare variables
    userInput = ""  # this variable is a string
 
    # get data from user
    userInput = input("Please enter a sentence: ")
 
    # display string
    print("\nYou Entered: '%s'" % (userInput))
 
if __name__ == "__main__":
    main()
# http://programmingnotes.org/

The following is similar to the other examples listed on this page, except we display the entire string instead of just simply the first character.

The resulting code should give following output

Please enter a sentence: Hello World! You Entered: 'Hello World!'

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Posted in: Console, Getting Started, Python, Python Tags: char, if/else, python, string

Python || Using If Statements & String Variables

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