Python Find String in List – Guide
We can use Python in operator to check if a string is present in the list or not. There is also a not in operator to check if a string is not present in the list.
l1 = ['A', 'B', 'C', 'D', 'A', 'A', 'C']
# string in the list
if 'A' in l1:
print('A is present in the list')
# string not in the list
if 'X' not in l1:
print('X is not present in the list')
Output:
A is present in the list
X is not present in the list
Let’s look at another example where we will ask the user to enter the string to check in the list.
l1 = ['A', 'B', 'C', 'D', 'A', 'A', 'C']
s = input('Please enter a character A-Z:\n')
if s in l1:
print(f'{s} is present in the list')
else:
print(f'{s} is not present in the list')
Output:
Please enter a character A-Z:
A
A is present in the list
Python Find String in List using count()
We can also use count() function to get the number of occurrences of a string in the list. If its output is 0, then it means that string is not present in the list.
l1 = ['A', 'B', 'C', 'D', 'A', 'A', 'C']
s = 'A'
count = l1.count(s)
if count > 0:
print(f'{s} is present in the list for {count} times.')
Finding all indexes of a string in the list
There is no built-in function to get the list of all the indexes of a string in the list. Here is a simple program to get the list of all the indexes where the string is present in the list.
l1 = ['A', 'B', 'C', 'D', 'A', 'A', 'C']
s = 'A'
matched_indexes = []
i = 0
length = len(l1)
while i < length:
if s == l1[i]:
matched_indexes.append(i)
i += 1
print(f'{s} is present in {l1} at indexes {matched_indexes}')
Output:
A is present in ['A', 'B', 'C', 'D', 'A', 'A', 'C'] at indexes [0, 4, 5]
Python Find String in List – Guide
