C语言学习-最大值、加减法交替、乘法口诀

1.求一组数的最大值

int arr[] = { 0,0,1,1,2,3,5,6,7,9,9 };
  int a = arr[0];
  int i = 0;
  int sz = sizeof(arr) / sizeof(arr[0]);
  for(i = 1; i < sz; i++)
  {
    if (a < arr[i])
    {
      a = arr[i];

    }
  }
  printf("%d", a);

2.加减交替运算1/1-1/2+1/3-1/4.....

double a = 0;
  int i = 0;
  int flag = 1;
  for (i = 1; i <= 100; i++)
  {
    a += flag*1.0 / i;
    flag = -flag;
  }
  printf("%f", a);

3.乘法口诀打印

int i = 0;
  for (i = 1; i <= 9; i++)
  {
    int j = 0;
    for (j = 1; j <= i; j++)
    {
      printf("%d*%d=%-2d  ", i, j, i * j);
    }
    printf("\n");
  }