Multiple warnings on compile

[LeamHall]

$ make
cc ssv.c -o ssv  -lX11
ssv.c:260:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
  260 | main(argc,argv)
      | ^~~~
ssv.c: In function ‘main’:
ssv.c:274:33: warning: implicit declaration of function ‘usage’ [-Wimplicit-function-declaration]
  274 |   if ((argc > 3) || (argc < 2)) usage();
      |                                 ^~~~~
ssv.c:286:7: warning: implicit declaration of function ‘exit’ [-Wimplicit-function-declaration]
  286 |       exit(1); }
      |       ^~~~
ssv.c:70:1: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
   69 | #include "bitmaps/zhodane.xbm"
  +++ |+#include <stdlib.h>
   70 | 
ssv.c:286:7: warning: incompatible implicit declaration of built-in function ‘exit’ [-Wbuiltin-declaration-mismatch]
  286 |       exit(1); }
      |       ^~~~
ssv.c:286:7: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
ssv.c:290:7: warning: incompatible implicit declaration of built-in function ‘exit’ [-Wbuiltin-declaration-mismatch]
  290 |       exit(1); }
      |       ^~~~
ssv.c:290:7: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
ssv.c:297:7: warning: incompatible implicit declaration of built-in function ‘exit’ [-Wbuiltin-declaration-mismatch]
  297 |       exit(1); }
      |       ^~~~
ssv.c:297:7: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
ssv.c:301:7: warning: incompatible implicit declaration of built-in function ‘exit’ [-Wbuiltin-declaration-mismatch]
  301 |       exit(1); }
      |       ^~~~
ssv.c:301:7: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
ssv.c:305:7: warning: incompatible implicit declaration of built-in function ‘exit’ [-Wbuiltin-declaration-mismatch]
  305 |       exit(1); }
      |       ^~~~
ssv.c:305:7: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
ssv.c:388:5: warning: implicit declaration of function ‘print_subsector’ [-Wimplicit-function-declaration]
  388 |     print_subsector();
      |     ^~~~~~~~~~~~~~~
ssv.c:407:19: warning: implicit declaration of function ‘gen_sector’ [-Wimplicit-function-declaration]
  407 |                   gen_sector(win);
      |                   ^~~~~~~~~~
ssv.c:415:19: warning: implicit declaration of function ‘repaint_buttons’ [-Wimplicit-function-declaration]
  415 |                   repaint_buttons();
      |                   ^~~~~~~~~~~~~~~
ssv.c:419:41: warning: passing argument 1 of ‘XRefreshKeyboardMapping’ from incompatible pointer type [-Wincompatible-pointer-types]
  419 |               XRefreshKeyboardMapping ( &event);
      |                                         ^~~~~~
      |                                         |
      |                                         XEvent *
In file included from ssv.c:36:
/usr/include/X11/Xlib.h:3082:5: note: expected ‘XMappingEvent *’ but argument is of type ‘XEvent *’
 3082 |     XMappingEvent*      /* event_map */
      |     ^~~~~~~~~~~~~~
ssv.c:423:17: warning: implicit declaration of function ‘mark_border’ [-Wimplicit-function-declaration]
  423 |                 mark_border();
      |                 ^~~~~~~~~~~
ssv.c:463:33: warning: passing argument 1 of ‘XLookupString’ from incompatible pointer type [-Wincompatible-pointer-types]
  463 |               i = XLookupString(&event, text, 10, &key, NULL);
      |                                 ^~~~~~
      |                                 |
      |                                 XEvent *
In file included from ssv.c:37:
/usr/include/X11/Xutil.h:535:5: note: expected ‘XKeyEvent *’ but argument is of type ‘XEvent *’
  535 |     XKeyEvent*          /* event_struct */,
      |     ^~~~~~~~~~
ssv.c:471:3: warning: incompatible implicit declaration of built-in function ‘exit’ [-Wbuiltin-declaration-mismatch]
  471 |   exit(0);
      |   ^~~~
ssv.c:471:3: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
ssv.c: At top level:
ssv.c:474:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
  474 | gen_sector(d)
      | ^~~~~~~~~~
ssv.c:666:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
  666 | load_sector_file(argc, argv)
      | ^~~~~~~~~~~~~~~~
ssv.c: In function ‘load_sector_file’:
ssv.c:678:7: warning: incompatible implicit declaration of built-in function ‘exit’ [-Wbuiltin-declaration-mismatch]
  678 |       exit(1); }
      |       ^~~~
ssv.c:678:7: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’
ssv.c:695:7: warning: implicit declaration of function ‘load_bdr_seg’ [-Wimplicit-function-declaration]
  695 |       load_bdr_seg(line);
      |       ^~~~~~~~~~~~
ssv.c:703:18: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  703 |       t_start[4] = NULL;
      |                  ^
ssv.c:704:16: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  704 |       t_end[4] = NULL;
      |                ^
ssv.c:705:17: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  705 |       offset[4] = NULL;
      |                 ^
ssv.c:707:14: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  707 |       str[2] = NULL;
      |              ^
ssv.c:708:29: warning: implicit declaration of function ‘atoi’ [-Wimplicit-function-declaration]
  708 |       t_route[tr_cnt].x1 = (atoi(str) - 1) % 8;
      |                             ^~~~
ssv.c:710:14: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  710 |       str[2] = NULL;
      |              ^
ssv.c:713:14: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  713 |       str[2] = NULL;
      |              ^
ssv.c:716:14: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  716 |       str[2] = NULL;
      |              ^
ssv.c:720:14: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  720 |       str[2] = NULL;
      |              ^
ssv.c:729:14: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  729 |       str[2] = NULL;
      |              ^
ssv.c:746:18: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  746 |       w->name[0] = NULL;
      |                  ^
ssv.c:749:20: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  749 |       w->name[i+2] = NULL;
      |                    ^
ssv.c:753:15: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  753 |     w->hex[4] = NULL;
      |               ^
ssv.c:757:20: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  757 |     w->Starport[1] = NULL;
      |                    ^
ssv.c:768:15: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  768 |     w->uwp[8] = NULL;
      |               ^
ssv.c:772:16: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  772 |     w->Base[1] = NULL;
      |                ^
ssv.c:775:54: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  775 |     if ((w->notes[0] = line[32]) == ' ') w->notes[0] = NULL;
      |                                                      ^
ssv.c:778:58: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  778 |         if ((w->notes[2] = line[35]) == ' ') w->notes[2] = NULL;
      |                                                          ^
ssv.c:781:62: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  781 |             if ((w->notes[4] = line[38]) == ' ') w->notes[4] = NULL;
      |                                                              ^
ssv.c:784:66: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  784 |                 if ((w->notes[6] = line[41]) == ' ') w->notes[6] = NULL;
      |                                                                  ^
ssv.c:787:70: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  787 |                     if ((w->notes[8] = line[44]) == ' ') w->notes[8] = NULL;
      |                                                                      ^
ssv.c:790:38: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  790 |                         w->notes[10] = NULL;
      |                                      ^
ssv.c:799:16: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  799 |     w->Zone[1] = NULL;
      |                ^
ssv.c:803:22: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  803 |     w->allegiance[2] = NULL;
      |                      ^
ssv.c:807:12: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  807 |     str[1] = NULL;
      |            ^
ssv.c:812:12: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  812 |     str[2] = NULL;
      |            ^
ssv.c:815:12: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  815 |     str[2] = NULL;
      |            ^
ssv.c:820:12: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  820 |     str[1] = NULL;
      |            ^
ssv.c:831:12: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  831 |     str[1] = NULL;
      |            ^
ssv.c: At top level:
ssv.c:871:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
  871 | load_bdr_seg(str)
      | ^~~~~~~~~~~~
ssv.c: In function ‘load_bdr_seg’:
ssv.c:880:14: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  880 |   bdr_hex[2] = NULL;
      |              ^
ssv.c:884:14: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  884 |   bdr_hex[2] = NULL;
      |              ^
ssv.c:887:16: warning: assignment to ‘char’ from ‘void *’ makes integer from pointer without a cast [-Wint-conversion]
  887 |   edge_char[1] = NULL;
      |                ^
ssv.c: At top level:
ssv.c:900:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
  900 | print_sector_file()
      | ^~~~~~~~~~~~~~~~~
ssv.c:933:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
  933 | repaint_buttons()
      | ^~~~~~~~~~~~~~~
ssv.c:958:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
  958 | mark_border()
      | ^~~~~~~~~~~
ssv.c:1025:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
 1025 | print_subsector()
      | ^~~~~~~~~~~~~~~
ssv.c: In function ‘print_subsector’:
ssv.c:1049:16: warning: comparison between pointer and integer
 1049 |   if (PrintPix == NULL)
      |                ^~
ssv.c:1073:18: warning: implicit declaration of function ‘Get_Colors’ [-Wimplicit-function-declaration]
 1073 |   if ((ncolors = Get_Colors(&colors)) == 0)
      |                  ^~~~~~~~~~
ssv.c:1110:5: warning: implicit declaration of function ‘_swaplong’ [-Wimplicit-function-declaration]
 1110 |     _swaplong((char *) &header, sizeof(header));
      |     ^~~~~~~~~
ssv.c:1113:9: warning: implicit declaration of function ‘_swapshort’ [-Wimplicit-function-declaration]
 1113 |         _swapshort((char *) &colors[i].red, 3 * sizeof(short));
      |         ^~~~~~~~~~
ssv.c:1128:19: warning: implicit declaration of function ‘free’ [-Wimplicit-function-declaration]
 1128 |   if(ncolors > 0) free(colors);
      |                   ^~~~
ssv.c:1128:19: note: include ‘<stdlib.h>’ or provide a declaration of ‘free’
ssv.c:1128:19: warning: incompatible implicit declaration of built-in function ‘free’ [-Wbuiltin-declaration-mismatch]
ssv.c:1128:19: note: include ‘<stdlib.h>’ or provide a declaration of ‘free’
ssv.c: At top level:
ssv.c:1152:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
 1152 | Get_Colors(colors)
      | ^~~~~~~~~~
ssv.c: In function ‘Get_Colors’:
ssv.c:1159:29: warning: implicit declaration of function ‘malloc’ [-Wimplicit-function-declaration]
 1159 |   if ((*colors = (XColor *) malloc (sizeof(XColor) * ncolors)) == NULL)
      |                             ^~~~~~
ssv.c:1159:29: note: include ‘<stdlib.h>’ or provide a declaration of ‘malloc’
ssv.c:1159:29: warning: incompatible implicit declaration of built-in function ‘malloc’ [-Wbuiltin-declaration-mismatch]
ssv.c:1159:29: note: include ‘<stdlib.h>’ or provide a declaration of ‘malloc’
ssv.c: At top level:
ssv.c:1170:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
 1170 | _swapshort (bp, n)
      | ^~~~~~~~~~
ssv.c:1187:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
 1187 | _swaplong (bp, n)
      | ^~~~~~~~~
ssv.c:1210:1: warning: return type defaults to ‘int’ [-Wimplicit-int]
 1210 | usage()
      | ^~~~~
ssv.c: In function ‘usage’:
ssv.c:1213:3: warning: incompatible implicit declaration of built-in function ‘exit’ [-Wbuiltin-declaration-mismatch]
 1213 |   exit(1);
      |   ^~~~
ssv.c:1213:3: note: include ‘<stdlib.h>’ or provide a declaration of ‘exit’