return方法找不到符号

Question

public static int rowSum(int[][] d)
{
    for (int i = 0; i < d.length; i++)
    {
        int  sum = 0;
        for (int j = 0; j < d[i].length; j++)
        {
            sum = sum + d[i][j];
        }
    }
    return sum;
}
// says cant find symbol "sum"

Answer 1

是的,你试图使用你在一个无效的范围内定义的变量......

public static int rowSum(int[][] d)
{

  for (int i = 0; i < d.length; i++)
  {
     int  sum = 0;      //definition
     for (int j = 0; j < d[i].length; j++)
     {
        sum = sum + d[i][j];
     }
  } //scope of sum variable ends here

  return sum; //not valid access!!! sum is not defined here.
}   

把它放在外面一圈:

public static int rowSum(int[][] d)
{
  int  sum = 0;      //definition
  for (int i = 0; i < d.length; i++)
  {
     for (int j = 0; j < d[i].length; j++)
     {
        sum = sum + d[i][j];
     }
  }    
  return sum; //not valid access!!!
}   //scope of sum ends here

但是你还有另外一个问题......你给一个整数添加了两个值...我不确定你是否想要那个,即使你需要得到一个整数,我还要把它们作为双精度加上,并返回一个整数. ..