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Engineering LibreTexts

6.6: Looping and Counting

The following program counts the number of times the letter a appears in a string:

word = 'banana'
count = 0
for letter in word:
    if letter == 'a':
        count = count + 1
print(count)

This program demonstrates another pattern of computation called a counter. The variable count is initialized to 0 and then incremented each time an a is found. When the loop exits, count contains the result: the total number of a's.

Exercise 3:

 

Encapsulate this code in a function named count, and generalize it so that it accepts the string and the letter as arguments.