Why my method is returning the result in Boolean?

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void methods cannot return a value

I have the following method which returns either true or false but I do not understand why.

public bool Check(string s)
    return s.Length == 8 && s.Count(Char.IsUpper) == 1 && s.Any(Char.IsDigit);

Please help me understand.

Your code amended (it will crash on s == null) and commented:

public bool Check(string s)
    return                           // return true if and only if 
      s != null &&                   // s is not null and
      s.Length == 8 &&               // s has Length of 8 and
      s.Count(Char.IsUpper) == 1 &&  // s has exactly 1 Upper case letter and
      s.Any(Char.IsDigit);           // s has at least one digit 

If Statements and Booleans, How do you return a string in a Boolean method? Return boolean. Here we see a method that returns a boolean based on its arguments. We prefix the method with the word "is." This is a convention.Return. Info: The isValid method will return true if the three conditions it evaluates are all true. Otherwise it returns false.

You should read it like:

public bool Check(string s)
    // It would be worth to check for null
    if(s == null)
       throw new ArgumentNullException(nameof(s));

    // because of the && all criteria must be true
        s.Length == 8                  // is the length 8?
        && s.Count(Char.IsUpper) == 1  // the must be one uppercase character? (the trick is to execute the IsUpper for each character)
        && s.Any(Char.IsDigit);        // Does it contain any digit? (same here)

Instead of using string s, you should give it better names, like string password. Same for the method name... CheckPasswordConstraints

Java.lang.Boolean.toString() Method, You declare a method's return type in its method declaration. of the method returns the boolean value true or false , depending on the outcome of a test. Hmm, then maybe this method shouldn't really be sold as a validation check, or the docs should say that you need to use a try catch to return what you want to return. That, or just make a separate method called validate() implementing a try catch around parse() specifically for validation checking only, which would return something similar to what I wrote above

Returning a Value from a Method (The Java™ Tutorials > Learning , Use a more complex return object that encapsulates both concerns. Example: public interface IValidationResult { boolean isSuccess(); String getMessage(); }. The parseBoolean() method of Boolean Class is a built in static method of the class java.lang.Boolean which is used to convert a given string to its boolean value. Syntax: Boolean.parseBoolean(String value)

s.Count and s.Any are methods, which counts (or signals if there are any elements in collection), with regard to method passed as an argument, which has to accept element of a colletion as a parameter and return true.

Since string is collection of chars, you can use Any and Count.

Char.IsDigit and Char.IsUpper are just methods of signeature:

bool MethodName(char c);

so they can be used in LINQ methods.

So, to sum up:

Count(Char.IsUpper) - counts upper characters

Any(Char.IsDigit) - signals, if we have at least one digit in string.

Returning a Value from a Method, I would also like to mention the idea of Command Query Separation. Ideally,. Queries return a result (and don't have side-effects); Commands  A Boolean search is particularly helpful after running an initial search. For instance, if you run a search that returns lots of results that pertain to the words you entered but don't actually reflect what you were looking for, you can start introducing Boolean operators to remove some of those results and explicitly add specific words.

My value checker function needs to return both a boolean and a , Boolean expressions (a > b) evaluate to a boolean value -- if your method needs to The intent of the original example is to make a decision and return a result. Any method that is not declared void must contain a return statement with a corresponding return value, like this: return returnValue; The data type of the return value must match the method's declared return type; you can't return an integer value from a method declared to return a boolean.

Should my method return void or a bool to indicate it was successful , But if the function should return a value, make sure all execution paths do returning from a function as soon as we are certain what the outcome will be was first The expression count > 0 evaluates to a Boolean value, either True or False. When you have complex classes, you can expose public methods (or properties) that return calculated bool values. Return. Often: Developers will use the "Is" prefix, to indicate the type of result. This is a convention.

Return Boolean Evaluations, For a program to do anything interesting, it needs if-statements and booleans to control and so am I" if the score is 10 or more and temperature is 100 or more. The result is that the body runs if the expression (score < 5) is false, which Writing a method that returns a boolean is just like writing any method with a return. How to Return Object from a Method in JAVA. A method returns to the code that invoked it when it: Completes all the statements in the method; Reaches a return statement; or Throws an exception (covered later) Whichever occurs first between the last two. Make sure to declare a method’s return type in its method declaration. You can use the

Some Tips, Tricks, and Common Errors, Instead of using an if/else block to compare variable we can do it right inside the return statement with a comparison operator and minmal code. Fix the function  The primary difference is that the person calling the method with a return code needs to write code to handle success or failure, while the person calling the method needs to do nothing. If it works the next line will be executed but if it fails the exception continues. It takes work to ignore exceptions, but no work to ignore return codes.