Скачать или смотреть Debugging Pattern Printing in C: Fixing the * Square Printing Code

Learn how to effectively debug your C code for printing patterns. Fix issues with erasing characters in a 2D array and ensure your patterns are displayed correctly.
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This video is based on the question https://stackoverflow.com/q/63717413/ asked by the user 'uprspr' ( https://stackoverflow.com/u/14212777/ ) and on the answer https://stackoverflow.com/a/63717453/ provided by the user 'MikeCAT' ( https://stackoverflow.com/u/4062354/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Debugging Pattern Printing in C: Fixing the * Square Printing Code

When programming in C, we often face challenges that can lead to unexpected outputs, especially when dealing with arrays and string manipulation. One common problem is printing patterns using characters like "*" in a structured form. In this post, we’ll dive into a specific issue involving a pattern printing code that fails to produce the expected output due to incorrect manipulation of characters.

The Problem

In our scenario, the goal is to create a square pattern of size N x N using the character "*" while omitting (erasing) the middle section of the square. The value of N is required to be a power of 3 (like 3, 9, or 27).

Here’s what the expected output looks like:

For N = 3:

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

For N = 9:

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

As you can see, the challenge lies in correctly removing the middle section once the N x N array is created.

Identifying the Issue

In the provided code, we create a 2D array of characters initialized with "*" and aim to clear out the middle section using the eraseMiddle() function. However, the output of the program is not as expected. Instead of correctly displaying the middle section cleared out, we end up with a pattern that misses characters on the last row.

Code Breakdown

Here’s the initial code that implements the pattern printing:

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

Why It Fails

The problem lies in the use of strcpy. This function is intended for copying strings, and using it to overwrite single characters can lead to undefined behavior. Specifically, it writes a null-terminating character, which can mess with adjacent characters in the array.

The Solution

To fix the problem, we need to change how we assign values when erasing the middle section. Instead of using strcpy, we should directly assign the character using single quotes:

Correcting the Code

Replace the string manipulation lines in both functions as follows:

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

and initialize the stars array like this:

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

Updated Code Snippet

Here’s the revised version of the eraseMiddle function demonstrating the fixes:

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

Conclusion

After implementing these changes, your code should correctly print the desired pattern with the middle section erased as intended. Remember, when working with character arrays in C, always use character assignments rather than string manipulation functions like strcpy when you only need to change single characters.

With this technique, you'll enhance your debugging skills in C programming and improve your ability to create complex patterns. Happy coding!