编译时说
a.C:3: `main' must return `int'
a.C: In function `int main(...)':
a.C:3: `string' undeclared (first use this function)
a.C:3: (Each undeclared identifier is reported only once for each function it
appears in.)
a.C:3: parse error before `;' token
a.C:5: `str' undeclared (first use this function)