c - 交换/交换指针时的未定义行为

Question

我创建了动态数组。如果具有某些值，则填充。打印它。但是交换/交换指针后(任务是在特定条件下交换行)

条件取决于sumL。为了不浪费您的时间，我没有描述细节。

问题在于交换指针。

for ( k = 0; k < N - 1; k++ )
{
    for ( i = 0; i < N - 1; i++
       if (sumL[i] > sumL[i+1])
       {
           temp = sumL[i];            // works
           sumL[i] = sumL[i+1];
           sumL[i+1] = temp;

           temp = *a[i];              // doesn't work. Array is not the same: elements 
           a[i] = a[i+1];             // contain other values.
           *a[i+1] = temp;            /* What is wrong? */
      }
}

Answer 1

如果你想交换指针，那么它应该是这样的

temp = a[i]; a[i] = a[i+1]; a[i+1] = temp;

如果你想交换值，那么它应该是这样的

temp = *a[i]; *a[i] = *a[i+1]; *a[i+1] = temp;