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Check if a string contains uppercase, lowercase, special characters and numeric values
Given string str of length N, the task is to check whether the given string contains uppercase alphabets, lowercase alphabets, special characters, and numeric values or not. If the string contains all of them, then print “Yes”. Otherwise, print “No”.
Examples:
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Input: str = “#GeeksForGeeks123@”
Output: Yes
Explanation:
The given string contains uppercase characters(‘G’, ‘F’), lowercase characters(‘e’, ‘k’, ‘s’, ‘o’, ‘r’), special characters( ‘#’, ‘@’), and numeric values(‘1’, ‘2’, ‘3’). Therefore, the output is Yes.
Input: str = “GeeksForGeeks”
Output: No
Explanation:
The given string contains only uppercase characters and lowercase characters. Therefore, the output is No.
Time Complexity: O(N)
Auxiliary Space: O(1)
Below is the implementation of the above approach:
Regular expression to check if password is «8 characters including 1 uppercase letter, 1 special character, alphanumeric characters»
I want a regular expression to check that
a password must be eight characters including one uppercase letter, one special character and alphanumeric characters.
And here is my validation expression which is for eight characters including one uppercase letter, one lowercase letter, and one number or special character.
How I can write it for a password that must be eight characters including one uppercase letter, one special character and alphanumeric characters?
14 Answers 14
The regular expression you are after will most likely be huge and a nightmare to maintain especially for people who are not that familiar with regular expressions.
I think it would be easier to break your regex down and do it one bit at a time. It might take a bit more to do, but I am pretty sure that maintaining it and debugging it would be easier. This would also allow you to provide more directed error messages to your users (other than just Invalid Password ) which should improve user experience.
From what I am seeing you are pretty fluent in regex, so I would presume that giving you the regular expressions to do what you need would be futile.
Seeing your comment, this is how I would go about it:
Alphanumeric characters: Using the \w+ should match any letter and number and underscore.
Take a look at this tutorial for more information.
Detect if a string contains uppercase characters
Is there an alternative to using a regular expression to detect if a string contains uppercase characters? Currently I’m using the following regular expression:
It works fine but I often hear the old adage «If you’re using regular expressions you now have two problems».
7 Answers 7
RegEx seems to be overkill:
Although a regex this simple will probably work fine
although I suppose that in your case you’re not expecting non-ASCII letters in your string (considering its name).
using for loops, not as efficient and readable as the other methods pointed out, but for starters should work and provide a comprehensive way of doing this:
Basically, you iterate over your string and check for Upper Chars, then you can add logic as to what to do with the place where there is an Upper Char. For example, insert a space where the second upper case char is found and then use the ToLower method on the whole string.
Not the answer you’re looking for? Browse other questions tagged c# regex string or ask your own question.
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Regex for at least one uppercase letter, one lowercase, one number OR special character
The password validation requirements for my input field are as follows: «Password should contain at least one uppercase, one lowercase letter, one number OR special character».
This is the regex for 1 uppercase, 1 lowercase, 1 number AND one special character
2 Answers 2
I think you need a regex like this:
In [\d$@$!%*?&] you have at least one number OR one special character.
I think this one help you
Password must be 8 characters including 1 uppercase letter, 1 special character, alphanumeric characters
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Checking letter case (Upper/Lower) within a string in Java
The problem that I am having is that I can’t get my Password Verification Program to check a string to ensure that, 1 of the characters is in upper case and one is in lower case, it will check the whole string for one of the other and print the error message based on which statement it is checking.
I have looked over this site and the internet for an answer and I am unable to find one. This is homework.
Below is my current code.
9 Answers 9
To determine if a String contains an upper case and a lower case char, you can use the following:
This allows you to check:
Essentially, this works by checking if the String is equal to its entirely lowercase, or uppercase equivalent. If this is not true, then there must be at least one character that is uppercase or lowercase.
As for your other conditions, these can be satisfied in a similar way:
With suitable error messages as above.
()-_=+ through but those weren’t in the list of «special» characters.
A loop like this one:
Has an obvious logical flaw: You enter it if the first character is not lowercase, then test if the second character is not lower case. At that point you throw an error.
Instead, you should do something like this (not full code, just an example):
Of course the code snippet you provided, besides the faulty logic, did not have code to test for the other conditions that your «help» option printed out. As was pointed out in one of the other answers, you could consider using regular expressions to help you speed up the process of finding each of these things. For example,