C语言编程错误及分析记录

1. warning: the `gets' function is dangerous and should not be used.
   解释链接：http://stackoverflow.com/questions/1694036/why-is-the-gets-function-so-dangerous-that-it-should-not-be-used
2. error: expected ‘:’, ‘,’, ‘;’, ‘}’ or ‘__attribute__’ before ‘=’ token
   解释链接：http://stackoverflow.com/questions/1694036/why-is-the-gets-function-so-dangerous-that-it-should-not-be-used
3. warning: assignment makes pointer from integer without a cast [-Wint-conversion]
     while(dentp = readdir(dp) != NULL)
   这个warning是由于if中的条件表达式书写有误，如果不将其消除，会在执行期间引发段错误。将其改成如下形式：
   while((dentp = readdir(dp)) != NULL)
   因为条件运算符优先级高于赋值运算符。