Regular expression to check for two of three criteria

Question

I need to create a regular expression to match strings that satisfy any two of the following three criteria: at least one upper case letter, at lease one lower case letter, at least one number.

for example the following would be the result:

"TestString" = MATCH (upper & lower)
"TestSTring5" = MATCH (upper, lower, & number)
"teststring" = NO MATCH (lower)
"TESTSTRING" = NO MATCH (upper)
"teststring5" = MATCH (lower & number)
"345T" = MATCH (number & upper)

Answer 1

It will be more straightforward and easier to maintain if you create a separate regex for each condition.

pseudocode:

reHasUpper = /[A-Z]/ ;
reHasLower = /[a-z]/ ;
reHasNumber = /[0-9]/ ;

function validatePassword (pwd) {

  metRequirements=0;

  if (reHasUpper.test(pwd)) metRequirements++;
  if (reHasLower.test(pwd)) metRequirements++;
  if (reHasNumber.test(pwd)) metRequirements++;

  return metRequirements > 1;

}

Answer 2

That will be a huge regular expression.

You need to test for something like this (indented for readability only):

"[a-z].*[A-Z]|" +
"[A-Z].*[a-z]|" +
"[A-Z].*[0-9]|" +
"[0-9].*[A-Z]|" +
"[a-z].*[0-9]|" +
"[0-9].*[a-z]"

Answer 3

I would try something along the lines of:

([a-z][A-Z]|[A-Z][a-z]|[a-z][0-9]|[0-9][a-z]|[A-Z][0-9]|[0-9][A-z])

What this essentially does is check for any pairs along the lines of:

• a1
• 1a
• A1
• 1A
• aA
• Aa

Within your string. If none of those pairs match, it fails. Since you're looking for any two of the three criteria to be met, this works by looking for pairs of characters that match the criteria.