Check for Special Characters in String

Check for special characters in string

I suggest using RegExp .test() function to check for a pattern match, and the only thing you need to change is remove the start/end of line anchors (and the * quantifier is also redundant) in the regex:

var format = /[ `!@#$%^&*()_+\-=\[\]{};':"\\|,.<>\/?~]/;//            ^                                       ^   document.write(format.test("My@string-with(some%text)") + "<br/>");document.write(format.test("My string with spaces") + "<br/>");document.write(format.test("MyStringContainingNoSpecialChars"));

Check is string contains special characters and at least 2 characters amongs digit and letter

You can assert the 2 occurrences of a character or digit in the same lookahead, and then match at least a single "special" character.

Using a case insensitive pattern:

^(?=(?:[^a-z\d\n]*[a-z\d]){2})[a-z\d]*[~!@#$%^&*()_+<>•`{}\\][~!@#$%^&*()_+<>•`{}\\a-z\d]*$

The pattern matches:

• ^ Start of string
• (?:[^a-z\d\n]*[a-z\d]){2} Assert 2 occurrences of either a char a-z or a digit. The [^a-z\d\n]* part negates the character class using [^ to prevent unnecessary backtracking
• [a-z\d]* Match optional chars a-z or a digit
• [~!@#$%^&*()_+<>•`{}\] Match a special character
• [~!@#$%^&()_+<>•`{}\a-z\d] Match optional allowed chars
• $ End of string

Regex demo

Check for special characters (/*-+_@&$#%) in a string?

The easiest way it to use a regular expression:

Regular Expression for alphanumeric and underscores

Using regular expressions in .net:

http://www.regular-expressions.info/dotnet.html

MSDN Regular Expression

Regex.IsMatch

var regexItem = new Regex("^[a-zA-Z0-9 ]*$");

if(regexItem.IsMatch(YOUR_STRING)){..}

Regex pattern to check if string has no special characters - Java

You missed a \ before the -. You should use

^[a-zA-Z0-9_\-.]*$

See the demo

RegEx- first character should not contain special characters and subsequent characters should not contain few special characters

You were close. Just missing using ^ inside a character class to negate it, and maybe + instead of * to allow an empty string.

Match start of string: ^

Match a single character that's not one of !@#$%^&*()_+-=[]{};':"|,.<>/?: [^!@#$%^&*()_+\-=\[\]{};':"\\|,.<>\/\?]

Match a string of any length that doesn't contain one of !@$%^*+=[]{};:|<>?: [^!@$%^*+=\[\]{};:\\|<>\?]*

Match end of string: $

Complete regex: ^[^!@#$%^&*()_+\-=\[\]{};':"\\|,.<>\/\?][^!@$%^*+=\[\]{};:\\|<>\?]*$

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