#include int main() { int a = 0; int b = 40; int c = 2; // See: https://gcc.gnu.org/onlinedocs/gcc-4.3.0/gcc/Nested-Functions.html inline void lf(register int* r) { a += *r; }; // semicolon(;) not needeed! /* // Same as above... but need auto storage class if you pre-declare inline auto void lf(register int* r); inline void lf(register int* r) { a += *r; }; // semicolon(;) not needeed! */ lf(&b); lf(&c); printf("%d\n", a); }