Determine Which Characters Are Letters MATLAB

This tutorial will discuss determining which characters are letters using the `isletter()` function in Matlab.

Check Which Characters Are Letters Using the `isletter()` Function in MATLAB

A string or array of characters can contain letters, and numbers like the address of a house can contain letters as well as numbers. If we want to find if the given character, character array, or string contains a letter, we can use Matlab’s built-in function `isletter()`.

In the case of single character input, the `isletter()` function returns 1 or 0 depending on the character. If the character is a letter, the `isletter()` function will return one or true, and if the character is not a letter, then the `isletter()` function will return 0 or false.

For example, let’s check a given character if it’s a letter or not. See the code below.

``````c = '5';
isletter(c)
``````

Output:

``````ans =

logical

0
``````

In the output, the result is 0, which means the given character is not a letter.

We can also check if a string or array of characters contains letters or not. If a character inside the string or array of characters is a letter, then the `isletter()` function will return 1 in its place and 0 elsewhere.

For example, let’s create a string containing letters as well as numbers and check how many letters are present inside the string. See the code below.

``````c = '25 street';
isletter(c)
``````

Output:

``````ans =

1×9 logical array

0   0   0   1   1   1   1   1   1
``````

In the output, we can see that the first three characters are not letters because the output is 0 on the first three places, and the rest of the characters are letters because the rest of the output contains ones.

Space is also considered a character that why we can see output contains a 0 at the place of the space.

The input can be a scalar, vector, matrix, or multidimensional array. The output will be a logical array.

The `isnumeric()` function can be used to check if the input is a number or not, and `isstring()` function can be used to check if the input is a string or not.

We can also perform operations on the input string after finding if it contains a letter or not.

For example, consider we want to extract the letters present in a string. In this case, we can use the `isletter()` function to check if the letters are present in the string or not.

If letters are present in the string, we will find their indices using the `find()` function, and then we can extract them using these indices. See the code below.

``````OldString = '25 street'
l = isletter(OldString);
indices = find(l==1);
NewString = OldString(indices)
``````

Output:

``````OldString =

'25 street'

NewString =

'street'
``````

In the output, the new string only contains letters.

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