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What Is a Semantic Error?

It Itches Like a Bug!

Related Questions

What Is a Semantic Error? A semantic error is a problem in your code that prevents the interpreter from understanding it. There may not be anything wrong with the logic you’ve written, but it will cause the program to crash the way you’ve written. For instance, the following code will produce an incorrect result in a Semantic runtime Error:

var a = 1 // No error

var b = 2 // No error

var c = 3 // No error

a + c = b

A semantic error is a language-level error in a program, typically when you try to use an identifier that has not been previously defined.

Semantic errors are detected at compile time, and you can think of them as static analysis errors.

For example, if you try to execute a variable that you have not declared, it will throw a semantic error:

A semantic error occurs when a programmer writes code that fails to communicate its intended purpose.

This is different from a syntax error, which occurs when the code is syntactically correct but does not perform its designed task.

In other words, a semantic error refers to an incorrect program that produces a result that doesn’t make sense.

For example, if a weather app said “Warm and sunny” even when outside it was raining, this would be a semantic error. The program did not produce what it was supposed to produce.

In other words, a semantic error refers to an incorrect program that produces a result that doesn’t make sense.

For example, if a weather app said “Warm and sunny” even when outside it was raining, this would be a semantic error. The program did not produce what it was supposed to produce.

What Is a Semantic Error?

A semantic error is a programming error that occurs when a line of code violates the semantics of the language. In other words, it’s an error that comes from the language being misused rather than getting the syntax wrong.

For example, that would be a semantic error if you told someone to go to your house and knock on the door, but they knocked on your neighbor’s door instead.

Semantic errors are less common than syntax errors because they can only occur when misusing a programming language.

Syntax errors are more common because they can happen in several ways:

  • Forgetting a punctuation mark.
  • Misspelling a keyword.
  • Missing semicolons.
  • Using undeclared variables before it’s defined.

Semantic errors usually cause unexpected behavior in your program.

Since there’s no way to know how your program should behave without knowing what it does, this type of error is especially tricky to find and fix.

Suppose you’re writing code for someone else to use (or even just for yourself). In that case, it’s best practice to test every line number before adding any new functionality so that all of your variable names are correctly defined, and all of your functions work as expected.

What Is a Dynamic Semantic Error?

Dynamic Semantic Error
Dynamic Semantic Error

A dynamic semantic error is a mistake that occurs when you’re writing based on your understanding of the meaning of words in a brief.

Dynamic semantic errors are different from static semantic errors, which are errors caused by misunderstanding what words mean in general.

A static semantic error might occur if you didn’t know the difference between “their” and “there,” for example, or if you wrote that someone was “irregardless” of something.

A static semantic error might include not understanding the nuances between similar words but having different meanings, like using “affect” instead of “effect.”

Dynamic semantic errors occur when you misunderstand the meaning of a word in a specific context. For example, if a brief says that the product is designed with an emphasis on “superiority,” but you write that it’s designed with an emphasis on “surgery.”

Dynamic semantic errors are a type of runtime errors that occur when you try to call a method on an object that doesn’t have such a method.

For instance, if you were to try to call the “reverse” method on an integer variable, the interpreter would throw a dynamic semantic error because integers don’t have a reverse method.

What Is A Static Semantic Error?

Static Semantic Error
Static Semantic Error

Static semantic errors are errors that the compiler detects before executing the program (compile-time errors).

These errors include: 

  • Incorrectly using a variable that has not been defined. 
  • Incorrectly using an operator, like forgetting to provide an argument for a minus sign. 
  • Defining or using a variable or function without declaring its type (JavaScript does not have static typing). 
  • Not providing the correct return type for a function.

A static semantic error is a type of bug that a compiler detects. It’s not necessarily a mistake in code syntax, but it might not be possible to execute the program as written.

In this case, fixing a static semantic error requires changing the code to be less ambiguous or more clearly defined.

For example, in Java, you can’t divide two integers and then assign the result to a variable of type boolean.

The compiler will flag this as an error and prompt you to correct it before execution.

Are Semantic Errors and Syntax Errors Same?

Semantic Error vs Syntax Error
Semantic Error vs Syntax Error

No, they are not the same. Programming in C++ can be a challenge. The language can be quirky, and there are many ways to make mistakes. There are two categories of error: syntax errors and semantic errors (logic errors).

Programming in C++ can be tricky since the language is somewhat quirky. It’s easy to make errors, especially when syntax errors mix with logic errors.

Semantic errors are similar to syntax errors because both cause your program to fail, but there’s a fundamental difference.

Semantic errors are bugs in your code that the interpreter does not catch, preventing your program from running.

Syntax error messages are bugs that prevent your computer’s program from running because of a coding mistake. The Python interpreter will find them because it knows the language’s syntax rules and can identify where you’ve failed to follow them.

Syntax errors are easy for an experienced developer to spot because they are obvious mistakes.

Difference Between Syntax and Semantic errors


  • “Syntax” refers to rules and regulations for writing statements in programming languages like C/C++.
  • The statement does not make any sense.
  • A statement is syntactically valid if it follows the appropriate rules for grammar
  • Grammar and syntax are essential in the language.


  • It’s a short form of ‘computer language.’
  • The meaning behind a sentence dictates how the program executes.
  • Errors are handled at runtime.

Final Words

To avoid semantic errors, it is important to ensure that your code is understandable by the interpreter. You can do this by writing clearly and consistently.

It is also important to note that you should follow logical patterns in your program to help prevent ambiguity. It can also be helpful to check your output while debugging to ensure that it matches your expectations.

The language and structure of most programming languages require every instruction, function, or statement to have an exact match with a ‘precise’ name. Very few things are ambiguous in the source code.

But because of this strictness, a syntax error occurs when there is no exact match for something you have written. These semantic errors typically come about when you use ‘dynamic names’ in your program source code, like variables, functions, and control statements.

The interpreter is trying to find a way to relate what you wrote with everything else that’s available in the program; when it fails to do so, it will fail as well, throwing a semantic error as it does so.

Written by:
Editor-in-Chief and lead author at WhyDo

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