#include <stdio.h>
#include <string.h>
#include <stdlib.h>
int main() {
double* hextorgba(char *hexstr)
{
  int hexstrlen=strlen(hexstr)/2;
  if (hexstrlen > 4)
  {
    printf("Invalid colour");
    exit(1);
  {

  static double rgba[4];
  rgba[3] = 255;

  int i;
  for (i=0;i<hexstrlen;i++)
  {
    char tmpstr[2];
    tmpstr[0]=hexstr[i*2];
    tmpstr[1]=hexstr[i*2+1];
    rgba[i] = strtol(tmpstr, 0, 16);
  }
  printf("RGBA(%d, %d, %d, %d)\n", (int)rgba[0], (int)rgba[1], (int)rgba[2], (int)rgba[3]);
  return rgba;
}
hextorgba("7f11e0");
}

           […] For example, -std=c90 turns off
           certain features of GCC that are incompatible with ISO C90, such as the "asm" and
           "typeof" keywords, but not other GNU extensions that do not have a meaning in ISO
           C90, such as omitting the middle term of a "?:" expression.