Troubleshooting String Comparisons in C: A Guide to strcmp

Having trouble with string comparisons in C programming? Learn how to fix common issues with `strcmp` and make your code more robust and readable!
---
This video is based on the question https://stackoverflow.com/q/70669692/ asked by the user 'thomas rocheteau' ( https://stackoverflow.com/u/14119857/ ) and on the answer https://stackoverflow.com/a/70669752/ 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: Comparisons between two strings don't work

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/licensing
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/by-sa/4.0/ ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Troubleshooting String Comparisons in C: A Guide to strcmp

As a programmer, you might find yourself wrestling with string comparisons in C, especially when trying to make decisions based on user input. String handling can often be tricky, particularly if you're not aware of certain intricacies. In this post, we’ll address a common issue associated with comparing strings in C and provide clear solutions to ensure your program behaves as expected.

The Problem: Inaccurate String Comparisons

Imagine you've designed a menu-based application where users can choose from different options by typing in their selection. You've implemented string comparisons to take the corresponding action based on user input, but when testing your code, you notice that the comparisons don't behave as anticipated. For instance, even when you enter the string "Pendu," the program jumps to the default case instead of executing the intended function.

Sample Code Snippet

Here’s the fragment of code where the problem lies:

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

Despite typing "Pendu," the execution does not behave as expected. The reason for this lies in how the input is processed and stored.

Understanding the Root Cause

The core issue stems from two main points:

The fflush(stdin) Function:

Using fflush on stdin leads to undefined behavior in C. It's essential to avoid this practice as it can yield unpredictable outcomes in your program.

Newline Characters:

When using fgets to read user input, the function captures the entire line, including the newline character ('\n') when the user presses the enter key. This character can interfere with string comparisons, causing them to return unexpected results.

Example Input Scenario

Let’s say the user enters "Pendu" followed by hitting enter. fgets captures "Pendu\n" in the choix_utilisateur variable. When strcmp checks choix_utilisateur against the string "Pendu," it sees a difference because of the newline character, thus failing the comparison.

The Solution: Removing the Newline Character

To address these issues, you can implement the following solutions:

Step 1: Remove the Newline Character

Add a line of code that effectively removes the newline character added by fgets. You can use the strcspn function to achieve this:

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

Step 2: Improve Readability in Comparisons

To make your conditions easier to read, consider using the following format for your string comparison:

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

This method explicitly compares the two strings and is generally easier for others reading your code to follow.

Final Implementation Example

Here’s how your improved code might look:

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

Conclusion

By removing the newline character and clarifying your string comparisons, you can prevent issues caused by improper string handling in C. Avoiding fflush(stdin) and using strlen appropriately will help you create more robust and error-free code. Embrace these best practices, and your string comparisons will result in a smoother user experience! Happy coding!

Видео Troubleshooting String Comparisons in C: A Guide to strcmp канала vlogize