Fixing the bsearch() Implementation for Arrays of Strings in C

Learn how to resolve issues with the `bsearch()` function when working with arrays of strings in C by using the correct pointer manipulation techniques. --- This video is based on the question https://stackoverflow.com/q/72417866/ asked by the user 'Eli Freid' ( https://stackoverflow.com/u/16328156/ ) and on the answer https://stackoverflow.com/a/72418089/ provided by the user 'chqrlie' ( https://stackoverflow.com/u/4593267/ ) 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: Problem with bsearch() implementation with array of strings 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. --- Troubleshooting bsearch() Implementation for Arrays of Strings in C When venturing into the realm of C programming, particularly when handling data with powerful search algorithms like bsearch(), you may encounter some challenges. One common problem arises when implementing the binary search function for arrays of strings. This article addresses a practical coding issue faced by many developers and provides a clear solution. The Problem In this case, the developer was trying to create a version of bsearch() to efficiently locate strings within an array of strings. The code seemingly worked well for arrays of integers but failed to yield results for an array of char * (strings). The function returned NOT_FOUND even when the string was present in the array. Here’s the structure of the original code that was causing the issue: [[See Video to Reveal this Text or Code Snippet]] The Cause of the Issue The root cause of the problem was that the comparison function was incorrectly interpreting the pointers passed to it. When you handle an array of strings, the binary search function must access the actual strings, not the pointers pointing to those strings. The comparison function was designed to accept a single pointer; however, the way the pointer manipulation was done within the binSearch function was incorrect. Implementing the Solution To correct this, you need to amend your comparison function to properly dereference the string pointers. Here’s the updated code that resolves this issue: Updated Comparison Function Replace the original comparison function with the following code: [[See Video to Reveal this Text or Code Snippet]] Updated Binary Search Function Call Additionally, the call to binSearch() in your stringBinSearch function should also be modified: [[See Video to Reveal this Text or Code Snippet]] Breaking Down the Fix Pointer Dereferencing: By changing the comparison function, we ensure that the inputs to strcmp are the actual strings rather than the pointers themselves. This is achieved by dereferencing the pointers within compareByAscii. Element Size: The ElemSize parameter must be set to sizeof(char *) instead of a fixed size like 100. This ensures that the binary search correctly calculates the positions in the array based on the sizes of the pointers. Passing the Item: When passing the target string to binSearch(), ensure that the address of the string is taken using the & operator. This allows the function to access the string value correctly. Conclusion By understanding the underlying issues with pointer manipulation and proper dereferencing in your C code, you can effectively implement the bsearch() function for any data type, including strings. Remember that managing pointers is crucial in C programming, especially when working with dynamic data types like strings. With these corrections, your search for strings within an array should now function flawlessly. Thank you for joining us in this debugging journey! Happy coding!