Runtime Error 9: Subscript Out of Range

This essay discusses the runtime error 9: subscript out of range, its causes, solutions, software recommendations, frequently asked questions (FAQs), relevant tech terms, and some useful tips.

Nene Aly

By Nene Aly / Updated on March 5, 2024

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The runtime error 9: subscript out of range is a common issue that occurs when the script tries to access an array element that doesn't exist or is outside the defined range. This error can result in program termination and can be frustrating for developers.

Causes of Runtime Error 9

There are several causes of the runtime error 9: subscript out of range. These include:

  • Trying to access an array element with an index that is out of range: This occurs when the index provided is greater than the size of the array or less than zero.
  • Using an undefined array: This occurs when an array is not properly initialized or declared.
  • Passing incorrect arguments to a function or procedure: If the function or procedure expects an array but receives something else, it can result in a runtime error 9.

Solutions to Runtime Error 9

When encountering the runtime error 9: subscript out of range, it is essential to follow these steps to resolve the issue:

  1. Check the array bounds: Verify that the index used to access the array is within its defined range. If not, adjust the index accordingly.
  2. Ensure array initialization: Make sure that the array is initialized correctly before accessing its elements. Initialize it with the appropriate size and assign values to each element.
  3. Verify function/procedure arguments: Check if the correct arguments are being passed to the function or procedure. If an array is required, ensure that an array is passed.
  4. Use error handling: Implement error handling mechanisms such as try-catch blocks to handle runtime errors gracefully. Display useful error messages to assist with debugging.
  5. Use debugging tools: Utilize debugging tools provided by the programming language or integrated development environment (IDE) to identify the source of the error. Step through the code to pinpoint the problematic area.

Software Recommendations

In dealing with the runtime error 9: subscript out of range, the following software tools are recommended:

Visual Studio Code:

Visual Studio Code is a popular source-code editor that provides excellent debugging features. It allows programmers to set breakpoints, inspect variables, and track the execution flow, making it a valuable tool for identifying and resolving runtime errors like subscript out of range.


Eclipse is an integrated development environment widely used for Java programming. It offers advanced debugging capabilities and allows developers to identify and fix errors efficiently.


PyCharm is a feature-rich integrated development environment designed specifically for Python. It provides powerful debugging tools that help programmers diagnose and fix runtime errors effectively.

Frequently Asked Questions (FAQs)

Here are some frequently asked questions related to the runtime error 9: subscript out of range:

Q: What is the runtime error 9: subscript out of range?

A: The runtime error 9: subscript out of range occurs when the script attempts to access an array element that does not exist or is outside the defined range.

Q: How can I fix the runtime error 9?

A: You can fix the runtime error 9 by checking array bounds, ensuring array initialization, verifying function/procedure arguments, using error handling, and utilizing debugging tools.

Q: Which programming languages are commonly affected by runtime error 9?

A: Runtime error 9 can occur in various programming languages such as C, C++, Java, Python, and Visual Basic.

Q: Can the runtime error 9 be caused by memory issues?

A: While the runtime error 9 is primarily related to accessing array elements, it can also be caused by memory allocation problems, such as insufficient memory or memory leaks.

Q: How can I prevent the runtime error 9 in my code?

A: To prevent the runtime error 9, ensure proper array initialization, validate user input, perform adequate error handling, and use efficient debugging techniques.

Q: Are there any tools to automatically detect runtime errors?

A: Yes, there are tools available, such as static analysis tools and code linters, that can help identify potential runtime errors during the development process.

Relevant Tech Terms

Before concluding, let's clarify a few relevant technical terms:

  • Array: An array is a data structure that stores a collection of elements of the same data type. It allows accessing elements using an index.
  • Index: The index is a numerical value used to represent the position of an element within an array. It starts from zero and increments by one for each subsequent element.
  • Error Handling: Error handling refers to the process of anticipating, detecting, and resolving errors in a program. It involves techniques and mechanisms to handle unexpected situations and prevent program termination.

Useful Tips

Here are some useful tips to prevent and resolve the runtime error 9: subscript out of range:

  • Regularly test and validate your code to catch errors early in the development cycle.
  • Avoid hardcoded array sizes and use dynamic memory allocation whenever possible.
  • Follow proper coding conventions and naming conventions to make your code more readable and maintainable.


The runtime error 9: subscript out of range can be a frustrating issue, but by following the provided solutions, leveraging recommended software tools, understanding relevant tech terms, and applying useful tips, developers can effectively prevent and resolve this error.

Nene Aly
Nene Aly · Editor