Check If String Contains Only Letters

Check if string contains only letters in javascript

With /^[a-zA-Z]/ you only check the first character:

• ^: Assert position at the beginning of the string
• [a-zA-Z]: Match a single character present in the list below:
  
  
  • a-z: A character in the range between "a" and "z"
  • A-Z: A character in the range between "A" and "Z"

If you want to check if all characters are letters, use this instead:

/^[a-zA-Z]+$/.test(str);

• ^: Assert position at the beginning of the string
• [a-zA-Z]: Match a single character present in the list below:
  
  
  • +: Between one and unlimited times, as many as possible, giving back as needed (greedy)
  • a-z: A character in the range between "a" and "z"
  • A-Z: A character in the range between "A" and "Z"
• $: Assert position at the end of the string (or before the line break at the end of the string, if any)

Or, using the case-insensitive flag i, you could simplify it to

/^[a-z]+$/i.test(str);

Or, since you only want to test, and not match, you could check for the opposite, and negate it:

!/[^a-z]/i.test(str);

JavaScript: check if a giving string contains only letters or digits

Add 0-9 also to your regex

 boolean onlyLetters(String str) {
   return str.match("^[A-Za-z0-9]+$");
 }

Java String - See if a string contains only numbers and not letters

If you'll be processing the number as text, then change:

if (text.contains("[a-zA-Z]+") == false && text.length() > 2){

to:

if (text.matches("[0-9]+") && text.length() > 2) {

Instead of checking that the string doesn't contain alphabetic characters, check to be sure it contains only numerics.

If you actually want to use the numeric value, use Integer.parseInt() or Double.parseDouble() as others have explained below.

---

As a side note, it's generally considered bad practice to compare boolean values to true or false. Just use if (condition) or if (!condition).

Checking if string is only letters and spaces - Python

A character cannot be both an alpha and a space. It can be an alpha or a space.

To require that the string contains only alphas and spaces:

string = input("Enter a string: ")

if all(x.isalpha() or x.isspace() for x in string):
    print("Only alphabetical letters and spaces: yes")
else:
    print("Only alphabetical letters and spaces: no")

To require that the string contains at least one alpha and at least one space:

if any(x.isalpha() for x in string) and any(x.isspace() for x in string):

To require that the string contains at least one alpha, at least one space, and only alphas and spaces:

if (any(x.isalpha() for x in string)
    and any(x.isspace() for x in string)
    and all(x.isalpha() or x.isspace() for x in string)):

Test:

>>> string = "PLEASE"
>>> if (any(x.isalpha() for x in string)
...     and any(x.isspace() for x in string)
...     and all(x.isalpha() or x.isspace() for x in string)):
...     print "match"
... else:
...     print "no match"
... 
no match
>>> string = "PLEASE "
>>> if (any(x.isalpha() for x in string)
...     and any(x.isspace() for x in string)
...     and all(x.isalpha() or x.isspace() for x in string)):
...     print "match"
... else:
...     print "no match"
... 
match

Check if string contains ONLY NUMBERS or ONLY CHARACTERS (R)

you need to persist your regex

all_num <- "123"
all_letters <- "abc"
mixed <- "123abc"

grepl("^[A-Za-z]+$", all_num, perl = T) #will be false
grepl("^[A-Za-z]+$", all_letters, perl = T) #will be true
grepl("^[A-Za-z]+$", mixed, perl=T) #will be false

How to check if a string only contains letters, numbers, underscores and period. Flutter/Dart

The problem with your RegExp is that you allow it to match substrings, and you match only a single character. You can force it to require that the entire string be matched with ^ and $, and you can match against one or more of the expression with +:

print(RegExp(r'^[a-z]+$').hasMatch(mainString));

To match all the characters you mentioned:

print(RegExp(r'^[A-Za-z0-9_.]+$').hasMatch(mainString));

---

Related Topics