Understanding the Mismatched Input ',' Expecting ')' Error in Pine Script

Описание: Learn how to resolve the common "mismatched input ',' expecting ')'" error in Pine Script while coding your trading indicators.
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Understanding the Mismatched Input ',' Expecting ')' Error in Pine Script

When working with Pine Script to create custom trading indicators, a common error you might encounter is the mismatched input ',' expecting ')' message. This typically indicates that there's a syntax issue in your code which needs to be resolved for the script to run properly.

Breaking Down the Error

The error message clearly points out that there is an unexpected comma (,) in your script, and the Pine Script compiler was expecting a closing parenthesis ()) instead. Understanding this error involves identifying where in your script the compilation expects the closure of parameters or function calls.

Common Scenarios Where the Error Occurs

Function Calls:

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In the example above, the sma function expects two parameters (source series and length), but an extra 20 along with a comma has been placed mistakenly. The corrected form would be:

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Indicator Plotting:

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Here, the xlabel function call is incorrectly placed as an additional argument. The intended format looks like passing multiple arguments improperly. The corrected version should be:

[[See Video to Reveal this Text or Code Snippet]]

Variable Definitions:

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Incorrectly typing or including extra arguments within variable declarations can also prompt this error. Ensure that all parameter lists are correctly formed. A corrected version might be:

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Tips to Prevent this Error

Verify Function Signatures: Always refer to the Pine Script documentation to confirm the required parameters and their order.

Check Parenthesis Matching: Ensure that every opening parenthesis (() has a corresponding closing parenthesis ()).

Assess Commas: Make sure commas are only used to separate parameters and not placed erroneously at the start or end of parameter lists.

Conclusion

The mismatched input ',' expecting ')' error is a common syntax issue in Pine Script. By carefully checking your parentheses and validating parameter lists against official documentation, you can effectively resolve and prevent this error, thus ensuring your trading indicators work smoothly.