Understanding and Fixing Errors in Dynamically Allocated Arrays in C

A guide to resolving common issues when working with dynamically allocated arrays in C, including practical coding examples. --- This video is based on the question https://stackoverflow.com/q/65186629/ asked by the user 'Yeyvoo' ( https://stackoverflow.com/u/14250338/ ) and on the answer https://stackoverflow.com/a/65186667/ provided by the user 'Vlad from Moscow' ( https://stackoverflow.com/u/2877241/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions. Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Errors while using dynamically allocated arrays Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l... The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license. If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com. --- Understanding and Fixing Errors in Dynamically Allocated Arrays in C When working with dynamically allocated arrays in C, it's not uncommon to encounter perplexing errors that can hinder your progress. One such issue arises when trying to handle multi-dimensional arrays. In this guide, we'll explore a specific problem a user faced while using dynamically allocated arrays and provide a step-by-step solution to fix it. The Problem The user encountered issues with their C code, where they were unable to print the value of Mat[0][0]. The main confusion stemmed from the incorrect usage of the scanf function when attempting to input values into their dynamically allocated array. Here is the specific problematic line in the provided code: [[See Video to Reveal this Text or Code Snippet]] This line of code is where the issue lies, and it prevents the correct assignment of values to the array elements. Let's break down how to solve this problem effectively. Identifying the Mistake The error arises from the way the user referenced array elements. The expression Mat + i + j does not correctly access the intended element of the 2D array. Instead, we need to ensure that we are directly accessing the correct pointer for the specific element located at the ith row and jth column. Correcting the scanf Call To fix the issue, we need to modify the scanf function call as follows: [[See Video to Reveal this Text or Code Snippet]] Explanation of the Correct Code: *(Mat + i) retrieves the pointer to the i-th row of the matrix. Adding j to this pointer effectively gives us a pointer to the j-th element of that specific row. Thus, this correction allows us to store the user input correctly into the desired location within the array. Full Code Example Here is the corrected portion of the user’s main function that demonstrates how the changes lead to proper functionality: [[See Video to Reveal this Text or Code Snippet]] Conclusion Dealing with dynamically allocated arrays can be challenging, especially with pointer arithmetic in C. However, understanding how to properly access elements is key to resolving issues like the one we've discussed. By correcting the scanf function call, we can ensure that the values are stored correctly in the dynamically allocated 2D array. For any additional questions or help related to dynamic memory allocation in C, feel free to reach out in the comments!