GNU C: Extensions to the C Language Family

Original post is here: eklausmeier.goip.de

Here is an article GNU C: Extensions to the C Language Family about extensions in GNU C vs. ANSI C.

1. Nested functions, i.e., a function defined within another function
2. Double-word integers, i.e., 64 bit signed and unsigned long long int and unsigned long long int
3. Arrays of variable length, f(int z) { int a[z]; }
4. Labeled elements in initializers
5. Case ranges, e.g., case 'A' ... 'Z'