{
      int n = 100;
      char *foo = malloc(n);
      ...;
      bar();
    }

    (gdb) break bar
    (gdb) r
    (gdb) up
    (gdb) p/x *(char (*)[100]) foo

Printing malloc'd arrays can be a pain. Using the "pointer to array of type" typecast, you can force gdb to tell you everything at once.