/in/foo.c: In function 'maopaopaixu':
/in/foo.c:7:9: warning: statement with no effect [-Wunused-value]
    7 |         for(i;i<len-1;i++){
      |         ^~~
/in/foo.c: In function 'main':
/in/foo.c:21:17: warning: format '%s' expects argument of type 'char *', but argument 2 has type 'char (*)[100]' [-Wformat=]
   21 |         scanf("%s",&str);
      |                ~^  ~~~~
      |                 |  |
      |                 |  char (*)[100]
      |                 char *
/in/foo.c:22:21: error: expected expression before 'char'
   22 |         maopaopaixu(char str[]);
      |                     ^~~~