C语言 读书笔记

1 基础相关

    1） 没有参数的函数应该注明void（参数位置）

    2） 判断某数是否是素数时，应先判断该数是否小于等于1（if(number <= 1)   /* 负数、0、1都不是素数*/）

    3） 计算两个数的最小公倍数：

           int f(int a,int b)

            {

                    int i;

                    for(i = 1;i < b;i++)

                    {

                            if((i*a) % b == 0)     return i*a;

                    }

                   return b*a;

            }

      4） 最大公约数算法：

          （1）//辗转相除法                                                               （2）     

                  int f(int a,int b)                                                                   int f(int a,int b)

                  {                                                                                          {

                          int r;                                                                                 while(a != b)

                          do{                                                                                    {

                                   r = a % b;                                                                      if(a > b)           {a = a - b ;}   

                                   a = b;                                                                             else if(b > a)   {b = b - a ;}

                                   b = r;                                                                         }

                          }while(r != 0);                                                                     return  a;

                          return a;                                                                       }

                  }

       5）数组的初始化：

            （1）一维数组的初始化：int a[10] = {};  int a[10] = {0};    //均可      int a[10] = {10 * 1}； //可以赋初值，但不是10个1

            （2）二维数组的初始化：int b[][3] = {{1,2,1},{2,1,1}};    int c[][3] = {{1,1,1},{},{1,2,3}};   //均可