Use alphanumericPattern to extract letters and digits from text.

Create txt as a string. Create pat as a pattern object that matches letters and digits using alphanumericPattern. Extract the pattern from txt.

txt = "abc 123 =+-*/";
pat = alphanumericsPattern;
alphanumerics = extract(txt,pat)

alphanumerics = 2x1 string
    "abc"
    "123"

Create txt as a string. Create pat as a pattern object that matches groups of three letters and numbers using alphanumericPattern. Extract the pattern from txt.

txt = "abcde123456_@#$";
pat = alphanumericsPattern(3);
alphanumerics = extract(txt,pat)

alphanumerics = 3x1 string
    "abc"
    "de1"
    "234"

Use alphanumericsPattern to match sets of letters and digits with a size that falls into specified range.

Create txt as a string. Create pat as a pattern object that matches groups of two to four letters and numbers using alphanumericPattern. Extract the pattern from txt.

txt = "12345ABCDE";
pat = alphanumericsPattern(2,4);

alphanumerics = extract(txt,pat)

alphanumerics = 3x1 string
    "1234"
    "5ABC"
    "DE"