嵌套 if() ... else VS if() .. else Ladder

与 if()...else 梯形图相比，嵌套的 if()...else 语句需要更多的执行时间（它们更慢），因为嵌套的 if()...else 语句在满足外部条件 if() 语句时检查所有内部条件语句，而 if()..else 梯形图将在任何一个时间点停止条件测试 if() 或 else if() 条件语句为真。

一个 if()...else 阶梯：

#include <stdio.h>

int main(int argc, char *argv[])
{
  int a, b, c;
  printf("\nEnter Three numbers = ");
  scanf("%d%d%d", &a, &b, &c);
  if ((a < b) && (a < c))
  {
    printf("\na = %d is the smallest.", a);
  }
  else if ((b < a) && (b < c))
  {
    printf("\nb = %d is the smallest.", b);
  }
  else if ((c < a) && (c < b))
  {
    printf("\nc = %d is the smallest.", c);
  }
  else
  {
    printf("\nImprove your coding logic");
  }
  return 0;
}

在一般情况下，被认为比同等的嵌套 if()...else 更好：

#include <stdio.h>

int main(int argc, char *argv[])
{
  int a, b, c;
  printf("\nEnter Three numbers = ");
  scanf("%d%d%d", &a, &b, &c);
  if (a < b)
  {
    if (a < c)
      {
        printf("\na = %d is the smallest.", a);
      }
    else
      {
        printf("\nc = %d is the smallest.", c);
      }
  }
  else
  {
    if(b < c)
    {
      printf("\nb = %d is the smallest.", b);
    }
    else
    {
      printf("\nc = %d is the smallest.", c);
    }
  }
  return 0;  
}