答案是90，但我没有得到解决方案？有人请帮忙 [英] It's answer is 90, but I didn't get the solution? Anyone please help

问题描述

  #include   <   stdio.h  >  
   int  main（）{
  int  a [] = { 10 ， 20 ， 30 ， 40  }; 
  int  i =  3 ，x; 
 x =  1  * a [ -  i] + 2 * a [ -  i] + 3 * a [ -  i]; 
 printf（ ％d，x）; 
  return   0 ; 
} 

我的尝试：



我在在线IDE工具上尝试了它并获得了答案90，但没有得到解决方案

解决方案

你处于灰色区域。代码建议

 x =  1  * a [i-  1 ] + 2 * a [i-  2 ] + 3 * a [i-  3 ]; 

但你没有保证，因为C编译器是一个重写器。

这意味着编译器可以自由重写这段代码更喜欢它。更糟糕的是，结果可能会随着另一个编译器而改变。



了解代码转换方式的唯一方法是在汇编级别使用调试器来查看它是如何编译的翻译

#include<stdio.h>
int main(){
    int a[]={10,20,30,40};
    int i=3,x;
    x=1*a[--i]+2*a[--i]+3*a[--i];
    printf("%d",x);
    return 0;
}

What I have tried:

I have tried it on Online IDE tools and getting the answer 90, but didnot get the solution

解决方案

You are in gray zone. the code suggest

x=1*a[i-1]+2*a[i-2]+3*a[i-3];

But you have no guaranty of that because C compiler is a rewriter.
This mean that the compiler is free to rewrite this code the way it prefer. Even worst, the result may change with another compiler.

The only way to know how the code is translated is to use a debugger at assembly level to see how it is translated.

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