compilation errors

[madeleineaaseremedios]

Hi! I encountered this error when trying to compile:

gcc -O3  -o ../anchors anchors.c skiplist.c
skiplist.c:12:37: warning: format specifies type 'unsigned int' but the argument has type 'void *' [-Wformat]
  printf("  %d   %x\n", tbp->index, tbp->myelem);
                 ~~                 ^~~~~~~~~~~
1 warning generated.
gcc -O3  -o ../chaos fchaos.c thrtrie.c skiplist.c global.c translate.c filebuffer.c -lm -DCHAOS__FLAG
fchaos.c:357:59: warning: data argument not used by format string [-Wformat-extra-args]
        fprintf(stderr, "WARNING %c converted to N\n", currchar, alpha);
                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~            ^
1 warning generated.
In file included from thrtrie.c:13:
./mempage.c:48:1: warning: non-void function does not return a value [-Wreturn-type]
}
^
1 warning generated.
skiplist.c:12:37: warning: format specifies type 'unsigned int' but the argument has type 'void *' [-Wformat]
  printf("  %d   %x\n", tbp->index, tbp->myelem);
                 ~~                 ^~~~~~~~~~~
1 warning generated.
global.c:172:1: warning: non-void function does not return a value [-Wreturn-type]
}
^
1 warning generated.
filebuffer.c:123:34: error: call to undeclared library function 'toupper' with type 'int (int)'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
    temp[i] = (strchr (alphabet, toupper ((char) i)) != 0) ?
                                 ^
filebuffer.c:123:34: note: include the header <ctype.h> or explicitly provide a declaration for 'toupper'
1 error generated.
make[1]: *** [../chaos] Error 1
make: *** [all] Error 2

Any help would be greatly appreciated!!