为什么它要执行两个“execute”语句？

Question

我取了一段更大的代码来强调。代码工作正常(很好的输出)，但我有一个问题。在下面的代码中，为什么会出现两个“如果”语句被执行呢？我了解到，拥有一系列'if‘语句与'else if’语句之间的区别在于，所有'if‘语句都被执行，但是当使用一系列'else if’语句时，当一个语句被执行时，程序就不会在该线程上继续运行。输入1，12，2，2执行下面的两个代码，但是它不是只执行第一个'else‘如果’语句‘吗？如果是这样的话，那么为什么会有ixlarge =4的输出呢？

          else if (x3 >= x4 && x3 >= x2 && x3 >= x1)
              xlarge = x3;
          else if(x4 >= x3 && x4 >= x2 && x4 >= x1)
              xlarge = x4;

#include <stdio.h>

int main( )
{
    int x1, x2, x3, x4;
    int xlarge, xsmall, ixlarge, ixsmall;

    while( 1 )
    {
        printf( "enter x1, x2, x3, x4:\n" );
        scanf( "%d%d%d%d", &x1, &x2, &x3, &x4 );

          xlarge = -1;
          xsmall = -1;
          if(x1 >= x2 && x1 >= x3 && x1 >= x4 )
              xlarge = x1;
          else if((x2 >= x3 && x2 >= x4 && x2 >= x1))
              xlarge = x2;
          else if (x3 >= x4 && x3 >= x2 && x3 >= x1)
              xlarge = x3;
          else if(x4 >= x3 && x4 >= x2 && x4 >= x1)
              xlarge = x4;

        printf("%d",xlarge);

          if(x1 == xlarge)
              ixlarge = 1;
          if(x2 == xlarge)
              ixlarge = 2;
          if(x3 == xlarge)
              ixlarge = 3;
          if(x4 == xlarge)
              ixlarge = 4;
        printf("%d",ixlarge);
         /*if(x3 == xlarge && x4 == xlarge)
             ixlarge = 4;*/


          if(x1 <= x2 && x1 <= x3 && x1 <= x4 )
              xsmall = x1;
          else if((x2 <= x3 && x2 <= x4 && x2 <= x1))
              xsmall = x2;
          else if (x3 <= x4 && x3 <= x2 && x3 <= x1)
              xsmall = x3;
          else if(x4 <= x3 && x4 <= x2 && x4 <= x1)
              xsmall = x4;

          
        
          if(x1 == xsmall)
              ixsmall = 1;
          if(x2 == xsmall)
              ixsmall = 2;
          if(x3 == xsmall)
              ixsmall = 3;
          if(x4 == xsmall)
              ixsmall = 4;
          if(x3 == xsmall && x4 == xsmall)
              ixsmall = 3;
          if(x2 == xsmall && x1 == xsmall)
              ixsmall = 1;
          if(x1 == xsmall && x3 == xsmall)
              ixsmall = 1;
          if(x1 == xsmall && x4 == xsmall)
              ixsmall = 1;
          if(x2 == xsmall && x3 == xsmall)
              ixsmall = 2;
          if(x2 == xsmall && x4 == xsmall)
              ixsmall = 2;
          if(x1 == xsmall && x3 == xsmall && x2 == xsmall)
              ixsmall = 1;
          if(x1 == xsmall && x4 == xsmall && x2 == xsmall)
              ixsmall = 1;

        printf( "largest = %4d at position %d, ", xlarge, ixlarge );
        printf( "smallest = %4d at position %d\n", xsmall, ixsmall );
    }

    return 0;
}

Answer 1

在输入为"1 1 2 2“的情况下，x3和x4的值都为2，因此这个块：

      else if (x3 >= x4 && x3 >= x2 && x3 >= x1)
          xlarge = x3;

是被执行的，尽管如果执行了另一个，xlarge仍然具有相同的值。表示x4最大的部分如下：

      if(x3 == xlarge)
          ixlarge = 3;
      if(x4 == xlarge)
          ixlarge = 4;

因为x3和x4具有相同的值，所以这两个if块都将执行，使得ixlarge的值为4。

您可以通过更改这组if语句来解决这个问题：

      if(x1 == xlarge)
          ixlarge = 1;
      if(x2 == xlarge)
          ixlarge = 2;
      if(x3 == xlarge)
          ixlarge = 3;
      if(x4 == xlarge)
          ixlarge = 4;

转至if/else

      if(x1 == xlarge)
          ixlarge = 1;
      else if(x2 == xlarge)
          ixlarge = 2;
      else if(x3 == xlarge)
          ixlarge = 3;
      else if(x4 == xlarge)
          ixlarge = 4;

并在设置ixsmall时执行类似的更改。

在一个边节点上，如果您使用数组和循环而不是4个单独的变量，您的代码可以使更简单、更容易出错。