Powershell: How To Test If A String Contains Uppercase Or Lowercase

The ^ at the start of the character class inverts the class, matching every character not included. Thereby this regular expression would only fail if the string contains upper-case letters somewhere. Still, the -cmatch is still needed.

Checks whether an array contains a value, an object contains a key, or a string contains a substring. The string comparison is case-sensitive. However, when testing if an object contains a key, the comparison is case-insensitive.

Powershell: How To Test If A String Contains Uppercase OrLowercase

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One way to verify for the uppercase letters is using the string library's isupper() function. If every character in current string is uppercase, this function returns True; otherwise, it returns False.

To do so, import the re library and install it if it isn't already installed. We'll use the regular expression "[A Z]+$" after importing the re library. If the string contains any characters other than uppercase characters, this will return False; otherwise, True will be returned.

Helm includes the following string functions:abbrev,abbrevboth,camelcase,cat,contains,hasPrefix,hasSuffix,indent,initials,kebabcase,lower,nindent,nospace,plural,print,printf,println,quote,randAlpha,randAlphaNum,randAscii,randNumeric,repeat,replace,shuffle,snakecase,squote,substr,swapcase,title,trim,trimAll,trimPrefix,trimSuffix,trunc,untitle,upper,wrap, andwrapWith.

Usually, we do not want all letters in a string converted into all lower or small case letters. Suppose we want the first letter of each word in a text to be in uppercase and rest all characters should be in lower case.

In this article, we explored the SQL UPPER function and SQL LOWER function to convert the characters in uppercase and lowercase respectively. We also create a custom function to convert first letter of each word in the text to capital letter.

Buried deep within the Prolog library is the very convenient predicate sub_atom_icasechk, which is a "half case-insensitive" check for a substring (half as in lowercase characters can match uppercase but not vice-versa). We just need to surround this in a check that all lowercase letters succeed this check.

The way this works is, for each alphabetic letter $i, we test whether the string contains $i or its upper-case equivalent ${i^} by removing all other characters. If this results in the empty string, then the input did not contain that letter, and we exit with 1 (false). If we have a non-empty result, then we passed the test and move on to the next letter. If the input string contains every English letter, we will reach the end of the program, thus exiting with 0 (true).

By default, -contains does a case-insensitive match. If you want to perform a case-sensitive search, use the -CContains operator. E.g. In the below example, the -CContains operator checks whether the test value exists in the collection considering its case:

In summary, the PowerShell contains operator or method is a useful tool in PowerShell for checking if a collection of objects, such as an array or a string, contains a specific value. You can use its simple syntax in a variety of situations to automate tasks and boost your work efficiency. In this article, we have discussed the PowerShell contains function to check if a string contains a specific substring. We have also learned through some examples how to use this function.

Basically, just split by the first lowercase character, then take the first item, and take all characters except the last character. This is assuming that the first lowercase character will always be after a space or an uppercase character that starts the word.

Even though we have some special characters and digits, the return is True as all our characters are indeed uppercase. This method returns True for whitespaces, digits and symbols, only lowercase letters return False.

Remember, we are looking for lowercase characters now, so even though we have a mix of upper and lower in this example, the return is True i.e. the string does contain lowercase so does not only have uppercase characters.

So we can now check to see if any of the characters in our string fall within the lowercase range (97-122), just to reiterate if we used the uppercase range it would flag not only lowercase characters but special characters and digits as well.

As we can see from our examples, our example_1 does contain lowercase alphabetic characters so we got a True return. Despite the fact, our example_2 contains special characters and digits we got a False return as there are no lowercase characters.

For legible passwords, Figure 1.1 highlights the characters to be used in the custom function. As a personal preference, lowercase l, uppercase I, the number 1, and the letter Q were excluded from the character array. The array was written out manually in lieu of Regex since there are excluded values; if all values were to be included, the array could be modified. There is no limit to the characters to include, but if this is to be shared over an encrypted email for example, then avoiding commonly misread characters may be advised.

With Regex queries, the format for matching character arrays corresponds to [array]{minimum,maximum}. For example, [a-z]{3,4} indicates that the password string must contain at least 3 but no more than 4 lowercase characters. When using the argument \d or \W this is indicative of digits and special characters respectively, so when examining the entire query the requirements specify that it must contain uppercase, lower case, special characters and numbers. At least 2 numbers and special characters and at least 2 uppercase letters must be included.

"string argument" - The default depends on the content of the very first search string. (Remember that is used to delimit search strings.) If the first search string is a valid regular expression that contains at least one un-escaped meta-character, then all search strings are treated as regular expressions. Otherwise all search strings are treated as literals. For example, "51.4 200" will be treated as two regular expressions because the first string contains an un-escaped dot, whereas "200 51.4" will be treated as two literals because the first string does not contain any meta-characters.

/G:file - The default depends on the content of the first non-empty line in the file. If the first search string is a valid regular expression that contains at least one un-escaped meta-character, then all search strings are treated as regular expressions. Otherwise all search strings are treated as literals.

When the search string contains multiple words, separated with spaces, then FINDSTR will return lines that contain either word (OR).

A literal search (/C:"string") will reverse this behaviour and allow searching for a phrase or sentence. A literal search also allow searching for punctuation characters.

convert the address to hex, but if the ith digit is a letter (ie. it's one of abcdef) print it in uppercase if the ith bit of the hash of the address (in binary form) is 1 otherwise print it in lowercase

Let's build a simple signup form with Angular and see how we can implement custom validation rules. Our form is going to have three input fields for the email address, password, and confirm password. The password requirements we want to fulfill are:Must be at least 8 characters longMust be alphanumeric, with at least one uppercase and one lowercase characterMust have at least one special characterPassword and Confirm Password must matchWe're going to validate these rules using Regular Expressions and give users visual feedback.I'm using the latest version of Angular, but you should be able to use the same code in previous releases. I'm assuming you have a basic understanding of Angular and Bootstrap, but even if you're new to Angular it shouldn't be hard to follow along. Before we get started, this is how the end result is going to look like.In this demo, we're going to use Bootstrap 4.6 and Bootstrap Icons 1.4 for the user interface. Feel free to use the UI framework of your choice.Getting StartedFirst, let's create a new Angular CLI project. Assuming you have Node.js, npm and Angular installed, execute the following command in your terminal (I'm on Windows and using PowerShell).ng new ng-password-validation-example --style=scss --routing=falseThis will create a new Angular project using SCSS styling, and no routing. Next, we install Bootstrap as our UI library. I'm using npm but you could use the package manager of your choice, like yarn.npm install --save bootstrapNext, we're going to import Bootstrap. I'm going to import the SCSS file directly, open src/styles.scss and add the following import:@import "~bootstrap/scss/bootstrap";Alternatively, you could update your angular.json file and add it to the styles section. Note that Bootstrap is imported before the application styles, otherwise, your overrides won't work ?."styles": [ "node_modules/bootstrap/scss/bootstrap.scss" "src/styles.scss"]Now we need an icon pack. I'm going to use Bootstrap Icons, but you could use FontAwesome, Material Icons, or any other. To keep things simple, I'll import it via CDN. Open src/index.html and add the following link in the head section:Lastly, we need to import the Reactive Forms Module since we're going to build a reactive form. Open app.module.ts and import the module:import { NgModule } from "@angular/core";import { BrowserModule } from "@angular/platform-browser";import { ReactiveFormsModule } from "@angular/forms";import { AppComponent } from "./app.component";@NgModule({ imports: [BrowserModule, ReactiveFormsModule], declarations: [AppComponent], bootstrap: [AppComponent]})export class AppModule { }Great, we have all we need in place. Now let's talk about custom validators before we build the signup form.Building Custom ValidatorsAngular provides built-in validators, and they're great for common use cases. But they're not going to help us achieve our requirements. We need a custom validator that uses RegEx (regular expression) to check individual rules and report back to us. So our custom validator needs to accept a RegEx, and a validation error object to return. For instance, if we wanted to check whether a string contains a digit or not, we want to write something like this:patternValidator(/\d/, { hasNumber: true }),Here, the method name is patternValidator. We're passing in the /\d/ regular expression and the second argument is the error object. Meaning if the target string didn't have a digit, the hasNumber error will be set on the form control. In the component template, we can check for control errors like control.hasError('hasNumber'). Nothing fancy here, basic stuff. Next, we'll create a class named PasswordValidators where we'll define our custom validation. Create the class manually, or use the Angular CLI:ng g class password-validatorsAll we need is a static method that accepts a regular expression and an error object. We're going to use the same method for each password rule, passing in different regular expressions. Here's the class definition:import { AbstractControl, ValidationErrors, ValidatorFn } from "@angular/forms";export class PasswordValidators { constructor() {} static patternValidator(regex: RegExp, error: ValidationErrors): ValidatorFn { return (control: AbstractControl): { [key: string]: any } => { if (!control.value) { // if the control value is empty return no error. return null; } // test the value of the control against the regexp supplied. const valid = regex.test(control.value); // if true, return no error, otherwise return the error object passed in the second parameter. return valid ? null : error; }; }}We also need a validator to check whether the password and confirm password values match. Add the following method to the class: static MatchValidator(control: AbstractControl) { const password: string = control.get("password").value; // get password from our password form control const confirmPassword: string = control.get("confirmPassword").value; // get password from our confirmPassword form control // if the confirmPassword value is null or empty, don't return an error. if (!confirmPassword?.length) { return null; } // if the confirmPassword length is < 8, set the minLength error. if (confirmPassword.length < 8) { control.get('confirmPassword').setErrors({ minLength: true }); } else { // compare the passwords and see if they match. if (password !== confirmPassword) { control.get("confirmPassword").setErrors({ mismatch: true }); } else { // if passwords match, don't return an error. return null; } } }Let's see what's happening in this method. First, we get the control values. If the confirm password is empty, we return null, meaning no errors were found. This is because the confirm password control is going to have additional validators defined on the FormGroup, we don't want to override them here. Next, we check the confirm password's length. If it's less than 8 characters long, we set the minLength error on the control. This is another validation rule defined on the form, which I'll get to in a minute. Lastly, if we have a value, we check whether the passwords match or not. If not, we set the mismatch error on the control, otherwise, we return null which means they do match. The error names are arbitrary, you could name them whatever you like.Building the Signup FormTo keep things simple and to the point, we're going to use the AppComponent itself. Open src/app/app.component.ts and update the class definition as follows:import { Component } from "@angular/core";import { FormControl, FormGroup, Validators } from "@angular/forms";import { PasswordValidators } from "./password-validators";@Component({ selector: "my-app", templateUrl: "./app.component.html", styleUrls: ["./app.component.scss"]})export class AppComponent { submitted = false; isWorking = false; signupForm = new FormGroup( { email: new FormControl(null, [Validators.email, Validators.required]), password: new FormControl( null, Validators.compose([ Validators.required, Validators.minLength(8), PasswordValidators.patternValidator(new RegExp("(?=.*[0-9])"), { requiresDigit: true }), PasswordValidators.patternValidator(new RegExp("(?=.*[A-Z])"), { requiresUppercase: true }), PasswordValidators.patternValidator(new RegExp("(?=.*[a-z])"), { requiresLowercase: true }), PasswordValidators.patternValidator(new RegExp("(?=.*[$@^!%*?&])"), { requiresSpecialChars: true }) ]) ), confirmPassword: new FormControl(null, [ Validators.required, Validators.minLength(8) ]) }, { validators: PasswordValidators.MatchValidator } ); // convenience getter for easy access to form controls get f() { return this.signupForm.controls; } get passwordValid() { return this.signupForm.controls["password"].errors === null; } get requiredValid() { return !this.signupForm.controls["password"].hasError("required"); } get minLengthValid() { return !this.signupForm.controls["password"].hasError("minlength"); } get requiresDigitValid() { return !this.signupForm.controls["password"].hasError("requiresDigit"); } get requiresUppercaseValid() { return !this.signupForm.controls["password"].hasError("requiresUppercase"); } get requiresLowercaseValid() { return !this.signupForm.controls["password"].hasError("requiresLowercase"); } get requiresSpecialCharsValid() { return !this.signupForm.controls["password"].hasError("requiresSpecialChars"); } onSubmit() { this.submitted = true; if (this.signupForm.invalid) { return; } this.isWorking = true; this.signupForm.disable(); setTimeout(() => { this.isWorking = false; this.signupForm.enable(); }, 1500); }}Nothing special going on, but let's see what we're doing here. First, we import FormControl, FormGroup, and Validators from @angular/forms. We also import the PasswordValidators class we just created. Then we define two properties on the component: submitted, and isWorking. The submitted property is used to check whether the form has been submitted or not. And the isWorking property is used to simulate an HTTP call (communicating with your API, creating an account, etc.). When you click the submit button, if the form is valid, we're going to disable the form, simulate a loading state, and reenable the form.The signupForm is a FormGroup composed of three controls: email, password, and confirmPassword. All three controls have a default value of null, this is important. If you were to set the default values to an empty string, the validators could behave unexpectedly. It's always best to set the default control values to null. The email control is simple and straightforward, it has two validators: email, and required. The confirmPassword control is simple too, it has two validators: required, and minLength(8). The password control is the interesting part. We're composing an array of validators using the Validators.compose method. The first two validators are built-in, required, and minLength. Then we define four custom validators using the static method we created. For each validation rule, we pass in a regular expression, and an error object to be set on the control if the RegExp didn't match. Right after the minLength validator, we define these rules:requiresDigit - the password must contain at least one digitrequiresUppercase - the password must contain at least one uppercase letterrequiresLowercase - the password must contain at least one lowercase letterrequiresSpecialChars - the password must contain at least one special characterLastly, we define a validator on the FormGroup itself for checking whether the passwords match or not:// control definitions removed for brevity.signupForm = new FormGroup( { email: new FormControl(), password: new FormControl(), confirmPassword: new FormControl() }, { // FormGroup validators go here. validators: PasswordValidators.MatchValidator });So far so good, we have created the signup form and defined our custom validators. Before we continue to the component template, we need some helper methods. This step is not necessary, you could achieve the same thing right in the template code. But that would be messy and clutters your markup. We need a few helper methods to easily access form controls and get the status of validation errors. Add the following methods to the AppComponent class:// convenience getter for easy access to form controlsget f() { return this.signupForm.controls;}get passwordValid() { return this.signupForm.controls["password"].errors === null;}get requiredValid() { return !this.signupForm.controls["password"].hasError("required");}get minLengthValid() { return !this.signupForm.controls["password"].hasError("minlength");}get requiresDigitValid() { return !this.signupForm.controls["password"].hasError("requiresDigit");}get requiresUppercaseValid() { return !this.signupForm.controls["password"].hasError("requiresUppercase");}get requiresLowercaseValid() { return !this.signupForm.controls["password"].hasError("requiresLowercase");}get requiresSpecialCharsValid() { return !this.signupForm.controls["password"].hasError("requiresSpecialChars");}The first one is a convenient method for easily accessing form controls. The other methods, return a boolean for each validation rule. For instance, the requiresDigitValid method returns true if the password control doesn't have the requiresDigit error.Component TemplateLet's start with the layout, since we're using Bootstrap we need a basic layout to display our form. Open src/app/app.component.html and add the following markup: We have a fixed container, a row with some top margin, and a single column. Next, we create a reactive form element as you normally would: The form is bound to the signupForm FormGroup defined in the component class. And the submit event is bound to the onSubmit method, which we'll define later on. For each form control, we define a Bootstrap form-group element, like so: Email address Email address is required Email address is not valid Pretty straightforward, but let's examine the code. Each form control has a label and an input field. The input fields are bound to the FormGroup using the formControlName directive. For validation feedback, we use Bootstrap to toggle CSS classes. The [ngClass] directive is used to add the appropriate class to the input fields. The is-valid class is added if the form control is dirty, or if the form has been submitted, but there were no errors on the control. Similarly, the is-invalid class is added if there are errors on the form control. The invalid-feedback block is from Bootstrap, and we simply display error messages for individual errors using the ngIf directive. Great, that was easy. Now let's see the custom validation UI.Password Rules Validation UIWhat we want to do is, first check whether we have a password or not. If not, we want to display a required error message. If we do have a password, display the UI for our custom validation rules. This is the markup for the password control: Password Password is required Must be at least 8 characters long Must contain at least 1 digit Must contain at least 1 uppercase character Must contain at least 1 lowercase character Must contain at least 1 special character If you follow the inline comments you can see that it's all self-explanatory. But let's see what's going on here. The label and the input field are the same as the other controls, nothing special. Then we have the invalid-feedback block, which is the container for validation errors. First, we check whether we have a password or not:Password is requiredIf the password control is empty, we want to display this error message and hide the others. Following that, we have another block that wraps the custom validation rules UI. I'll include just one of them here: Must be at least 8 characters long The validation-rules block is only displayed if we have a password, but the requirements aren't met. For each validation rule, we use our helper methods to see if we have an error or not. And based on that, we display an icon and a message. If there's an error, we use the text-danger (from Bootstrap) class to have the error message in red. Otherwise, we use the text-success class to have the message in green. For the icons, we use the tag, and based on the validation status, we toggle the icon class name. Here's the complete code for the component template: Email address Email address is required Email address is not valid Password Password is required Must be at least 8 characters long Must contain at least 1 digit Must contain at least 1 uppercase character Must contain at least 1 lowercase character Must contain at least 1 special character Confirm password Confirm your password Password must be at least 8 characters long Passwords do not match {{ isWorking ? 'Working on it...' : 'Create account' }} Now we need the submit handler. Add the onSubmit method to src/app/app.component.ts:onSubmit() { this.submitted = true; if (this.signupForm.invalid) { return; } this.isWorking = true; this.signupForm.disable(); setTimeout(() => { this.isWorking = false; this.signupForm.enable(); }, 1500);}First, we set the submitted property to true. This demo allows you to click the submit button to get the validation errors. Alternatively, you could disable the submit button until all validation requirements are met. Next, if the form is invalid (meaning there are errors on the form), the method returns, nothing happens. If the form is valid, we simulate an HTTP call. You'd call your API here, etc.Demo and Source CodeThat's it! Pretty cool. Angular is a powerful framework, and very flexible. You could use the same technique to implement your custom validation logic and enforce your business rules. If you want to learn more about form validation in Angular, have a look at these pages:Form ValidationReactive FormsCreating Async ValidatorsYou can find a demo to play with over here and see the complete code on StackBlitz.Updated at Sun Mar 21, 2021 Posted in Angular Tagged Tutorials QR Code Print Password Validation with Reactive Forms CloseAuthorArmin ZiaSoftware Engineer Leave a reply Comment body cannot be empty ? Name Email Website Please verify you are human ? Post comment ? Comment posted, thank you. It will go live after moderation. Reply body cannot be empty ? Name Email Website Please verify you are human ? Post reply 1 Replyrudra 7/12/2023 amazing Reply Reply posted, thank you. It will go live after moderation ?. 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