foo.c: In function ‘main’:
foo.c:7:11: warning: right-hand operand of comma expression has no effect [-Wunused-value]
    7 |    for(i=0,i<20,i++)
      |           ^
foo.c:7:20: error: expected ‘;’ before ‘)’ token
    7 |    for(i=0,i<20,i++)
      |                    ^
      |                    ;
foo.c:7:20: error: expected expression before ‘)’ token
foo.c:8:24: error: expected expression before ‘[’ token
    8 |            f[i]=f[i-1]+[i-2];
      |                        ^
foo.c:9:25: error: expected ‘)’ before ‘}’ token
    9 |         for(i=0;i<20;i++};
      |            ~            ^
      |                         )
foo.c:9:25: error: expected expression before ‘}’ token
foo.c: At top level:
foo.c:10:9: error: expected identifier or ‘(’ before ‘{’ token
   10 |         {
      |         ^
foo.c:14:11: error: expected declaration specifiers or ‘...’ before string constant
   14 |    printf("\n");
      |           ^~~~
foo.c:15:4: error: expected identifier or ‘(’ before ‘return’
   15 |    return 0:
      |    ^~~~~~