What is the problem of dangling else when does it arise?

What is the problem of dangling else when does it arise?

When the number of if statement is more or less then that of else statement confusion arises in matching by the compiler.. the problem so called is dangling else . It can be overcome by the use of braces.

What is dangling else problem in C++?

The dangling else is a problem in computer programming in which an optional else clause in an if–then(–else) statement results in nested conditionals being ambiguous. Formally, the reference context-free grammar of the language is ambiguous , meaning there is more than one correct parse tree .

How is the dangling else ambiguity resolved in C ++?

Java, C and C++ have chosen to resolve the Dangling-Else ambiguity uses the following rule: An else keyword always associates with the nearest preceeding if keyword that does NOT cause a syntax error.

What is dangling pointer in C with example?

Sometimes the programmer fails to initialize the pointer with a valid address, then this type of initialized pointer is known as a dangling pointer in C. Dangling pointer occurs at the time of the object destruction when the object is deleted or de-allocated from memory without modifying the value of the pointer.

How do you remove ambiguity from grammar explain with an example?

Methods To Remove Ambiguity-

1. By fixing the grammar.
2. By adding grouping rules.
3. By using semantics and choosing the parse that makes the most sense.
4. By adding the precedence rules or other context sensitive parsing rules.

What is dangling if else just mention the notation?

How do you get rid of dangling pointers?

The dangling pointer errors can be avoided by initializing the pointer to the NULL value. If we assign the NULL value to the pointer, then the pointer will not point to the de-allocated memory. Assigning NULL value to the pointer means that the pointer is not pointing to any memory location.

What is meant by dangling pointer?

A dangling pointer in IT is a pointer in code that leads to the wrong memory block or to some unintended destination. In many cases, this is because the original object that the pointer is pointing to has been deleted, moved or replaced.

How do you remove ambiguity in a sentence?

Expansion: Adding a word or two to the sentence can remove ambiguity. He finished the race last Thursday. —> He finished the race on last Thursday. 3.

How do I get rid of left recursion?

Left recursion is eliminated by converting the grammar into a right recursive grammar.

What is dangling else with example?

The dangling else is a problem in programming of parser generators in which an optional else clause in an if–then(–else) statement results in nested conditionals being ambiguous. Formally, the reference context-free grammar of the language is ambiguous, meaning there is more than one correct parse tree.

What is dangling-else problem with example?

This behavior can lead to what is referred to as the dangling-else problem. For example, if (x > 5 ) if (y > 5 ) System.out.println ( “x and y are > 5” ); else System.out.println ( “x is <= 5”); appears to indicate that if x is greater than 5, the nested if statement determines whether y is also greater than 5.

What is the dangling else problem in ALGOL?

The dangling else problem dates to ALGOL 60, and has been resolved in various ways in subsequent languages. In LR parsers, the dangling else is the archetypal example of a shift-reduce conflict .

How do you solve the if-else problem in programming languages?

The problem can also be solved by making explicit the link between an else and its if, within the syntax. This usually helps avoid human errors. Possible solutions are: Having an “end if” statement. Examples of such languages are ALGOL 68, Ada, Eiffel, PL/SQL, Visual Basic, and AppleScript.

What is the best way to solve the problem of if- statements?

Possible solutions are: Having an “end if” statement. Examples of such languages are ALGOL 68, Ada, Eiffel, PL/SQL, Visual Basic, and AppleScript. Disallowing the statement following a “then” to be an “if” itself (it may however be a pair of statement brackets containing only an if-then-clause).