Side-Effectful Expressions in C (2023)(blog.xoria.org)

  void *my_memcpy(void *dst, const void *src, size_t n)
  {
   const uint8_t *s = src;
   uint8_t *d = dst;
   for (size_t i = 0; i < n; i += 1) d[i] = s[i];
   return dst;
  }

  int powi(int x, int y)
  {
   int result = 1;
   for (int i = 0; i < y; i += 1) result *= x;
   return result;
  }

  void itoa(int n, char s[])
  {
   int i = 0;
   if (n < 0){
    n = -n;
    s[0] = '-', s += 1; // exclude from reverse
   }
   do{
    s[i] = n % 10 + '0', i += 1;
    n /= 10;
   }while(n > 0);
   s[i] = '\0';
   // reverse
   for(int j = 0, hi = i / 2; j < hi; j += 1) {
    i -= 1;
    char swap = s[j];
    s[j] = s[i];
    s[i] = swap;
   }
  }

  #include <stdio.h>
  #include <stdint.h>
  // insert functions
  int main(void){
   char src[] = "hello";
   char dst[10];
   my_memcpy(dst, src, sizeof(src));
   printf("%s == hello\n", dst);
   printf("%d == 27\n", powi(3,3));
   itoa(-12345, dst);
   printf("%s == -12345\n", dst);
   itoa(0, dst);
   printf("%s == 0\n", dst);
  }

  for (int i=0; i<n; ++i) // old
  for (int i=0; i<n; i+=1;) // new

  for (int i=0,j=n; i<j; ++i,--j) // old
  for (int i=0,j=n; i<j; {i+=1;j-=1;}) // maybe?

  for (int i=0,j=n; i<j; ;) {
    ...
    i+=1;
    j-=1;
  }