Print whether Qt 5's `QChar::isPrint()` is true for one or more code points

qisprint.cc

// g++ -fPIC -I/usr/include/qt5 -lQt5Core qisprint.cc -o qisprint

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include <QtCore/qchar.h>


void usage(char* prog) {
 fprintf(stderr, "Usage: %s <code point> [...]\n", prog);
}


int main(int argc, char** argv) {
 if (argc < 2) {
  usage(argv[0]);
  return 2;
 }
 
 for (int i = 1; i < argc; i++) {
  char* codepoint_str = argv[i];
  if (*codepoint_str == '\\')
   codepoint_str++;
  if (*codepoint_str == 'U' || *codepoint_str == 'u')
   codepoint_str++;
  if (*codepoint_str == '+')
   codepoint_str++;
  
  if (*codepoint_str == '-' || strlen(codepoint_str) > 8) {
   usage(argv[0]);
   return 2;
  }
  
  errno = 0;
  char* endptr;
  unsigned int codepoint = strtoul(codepoint_str, &endptr, 16);
  if (errno != 0) {
   perror("strtoul");
   return 1;
  } else if (endptr == codepoint_str || *endptr != '\0') {
   usage(argv[0]);
   return 2;
  }
  
  QChar qchar(codepoint);
  if (qchar.isPrint())
   printf("U+%04X is printable\n", codepoint);
  else
   printf("U+%04X is not printable\n", codepoint);
 }
 
 return 0;
}