Syntax Error Definition | The Interactive Glossary

Every programming language has it's own syntax, or set of rules that strictly define the combination of letters and symbols that can be used when writing the language. However, syntax isn't limited to just letters and symbols, it also defines the proper way that functions and commands must be structured.

When a command appears in a program's source code that does not conform to the programming language syntax, the code cannot be compiled, and the resulting error is called a syntax error.

It might be easier to understand syntax errors by looking at an example. Consider the following example from Wikipedia. In the programming language Java, the following statement is syntactically correct:

System.out.println("Hello World");

The following statement is very similar, but is incorrect and would produce a syntax error:

System.out.println(Hello World);

The only difference between the two statements is the presence of quotation marks around the string “Hello World”, and that one small error is enough to derail the program.

Depending on the programming language, the rules may be extremely strict, or they may be somewhat more relaxed. As you can imagine, syntax errors are more likely to occur in the extremely strict languages, making them harder to write and harder for new programmers to work with.

Also See: Programming Language, Java

Frequently Asked Questions

Where do syntax errors come into the picture on the web?

Many websites and web applications are built using programming languages such as PHP, Perl, Python, Ruby on Rails, JavaScript, Java, and ASP.NET. If syntax errors occur in the code that generates a website, the website may render some items incorrectly, may omit certain items, or may fail to load at all. In some cases, website visitors may actually see an error message advising them that there is a syntax error in the website files.

How do you find and fix a syntax error?

Fixing a syntax error involves finding the error and making adjustments to the code so that it is compliant with the syntax rules applicable to that programming language. Depending on the programming language and development environment, there are a number of software tools that will check for syntax errors, which can then be fixed by a programmer. Most programmers make use of an integrated development environment (IDE) that includes debugging tools which will catch most software bugs. If development tools aren't able to turn up the problem, there's no way around manually reviewing the code based on contextual clues about where the error might be and looking for mistakes in the code.

All of the debugging tools in the world won't keep syntax errors from occurring when programming languages are updated and the syntax changes. In those cases, the old code will have to be reviewed, rewritten, and brought up to current standards.

How can I avoid syntax errors?

If you have a website or application and are worried about causing syntax errors, here are a few tips to keep in mind:

• Do development work in a local development environment. Never tinker or modify live applications and websites. Instead, create a development environment on your local machine, and then push the changes to the live site once you've made a backup of the live site and are certain your updates are ready to go live.
• Use the debugging tools built into your IDE. While you may think you write clean code, it's always a good idea to make use of the debugging tools built into your IDE before signing off on a piece of code.
• Use an IDE that has time and mistake saving features, such as color-coding of properly written code, auto-correction of common syntax errors, and auto-completion of common commands. The right IDE will help you correct the majority of syntax errors before you ever try to compile the code.