feat: added 1.0.1 C release

Author: ntamas

_posts/2025-12-26-igraph-1.0.1-c.markdown

@@ -0,0 +1,28 @@
+---
+title: C/igraph 1.0.1
+date: 2025-12-26
+tags: c
+---
+
+[C/igraph](https://igraph.org/c/) 1.0.1, the first bugfix release of the 1.0 series, has arrived,
+with bug fixes and documentation improvements.
+
+As usual, the source can be obtained from [the GitHub releases page](https://github.com/igraph/igraph/releases/tag/1.0.1).
+
+A summary of changes in 1.0.1 is below.
+
+<!--more-->
+
+### Fixed
+
+- Eliminated references to `exit()` from the igraph shared library. These were accidentally introduced into igraph 1.0.0 through Qhull and Infomap.
+- Eliminated references to `std::cout` from the igraph shared library, as required by CRAN.
+- Fixed a bug in `igraph_hub_and_authority_scores()` that printed a warning about zero entries in the result even when the number of zeros was below the threshold used in the corresponding checks.
+- Fixed compilation and tests when Infomap support is disabled.
+- Fixed rare compilation issues on some Apple systems with some non-standard compilers due to incompatibilities between defining the `_POSIX_C_SOURCE` feature test macro and standard C++ headers. Now `_DARWIN_C_SOURCE` is defined when compiling igraph on Apple systems.
+- Fixed inconsistent libf2c prototypes for `s_copy()` and `s_cat()`. This restores compatibility with emscripten.
+
+### Other
+
+- Documentation improvements.
+- nanoflann was updated to version 1.9.0