Which of the following is an example of a secure coding guideline?

Using parameterized queries is an excellent example of a secure coding guideline. This approach helps prevent SQL injection attacks, which are among the most prevalent security vulnerabilities in web applications. When an application dynamically generates SQL queries using user input directly, it allows attackers to manipulate the query and potentially gain unauthorized access to the database.

Parameterized queries address this by separating SQL code from data input. Instead of concatenating user input directly into a SQL string, a parameterized query allows developers to define the SQL structure in advance and treat user input as parameters. This not only enhances security by ensuring that any user input is treated purely as data but also can improve performance and maintainability of the code as it can be reused.

In contrast, the other options represent practices that can lead to security vulnerabilities. For example, hard-coded passwords expose applications to significant risks, making it easy for attackers to gain access if they discover the password. Keeping all files public compromises data privacy and integrity, while ignoring user inputs increases the likelihood of allowing malicious data to enter the system, which could lead to exploitation. Overall, parameterized queries exemplify best practices in secure coding, prioritizing the protection of application data and integrity.