【C语言笔记】【有点逗系列】 一个打印 Hello, world! 的程序

【C语言笔记】【有点逗系列】 一个打印 Hello, world! 的程序

有点逗系列内容。用于记录各式各样有点逗甚至没有什么用的C语言用法☺。

功能说明

在网上看到了一个表面上很混乱但是实则没什么用处的打印 Hello, world! 的程序。

程序如下：

    main(){int i,n[]={(((1<<1)<<(1<<1)<<(1<<
    1)<<(1<<(1>>1)))+((1<<1)<<(1<<1))), (((1
    <<1)<<(1<<1)<<(1<<1)<<(1<<1))-((1<<1)<<(
    1<<1)<<(1<<1))+((1<<1)<<(1<<(1>>1)))+ (1
    <<(1>>1))),(((1<<1)<<(1<<1)<<(1<<1)<< (1
    <<1))-((1<<1)<<(1<<1)<<(1<<(1>>1)))- ((1
    <<1)<<(1<<(1>>1)))),(((1<<1)<<(1<<1)<<(1
    <<1)<<(1<<1))-((1<<1)<<(1<<1)<<(1<<(1>>1
    )))-((1<<1)<<(1<<(1>>1)))),(((1<<1)<< (1
    <<1)<<(1<<1)<<(1<<1))-((1<<1)<<(1<<1)<<(
    1<<(1>>1)))-(1<<(1>>1))),(((1<<1)<<(1<<1
    )<<(1<<1))+((1<<1)<<(1<<1)<<(1<<(1>>1)))
    -((1<<1)<<(1<<(1>>1)))),((1<<1)<< (1<<1)
    <<(1<<1)),(((1<<1)<<(1<<1)<<(1<<1)<<(1<<
    1))-((1<<1)<<(1<<1))-(1<<(1>>1))),(((1<<
    1)<<(1<<1)<<(1<<1)<<(1<<1))-((1<<1)<< (1
    <<1)<<(1<<(1>>1)))-(1<<(1>>1))), (((1<<1
    )<<(1<<1)<<(1<<1)<<(1<<1))- ((1<<1)<< (1
    <<1)<<(1<<(1>>1)))+(1<<1)), (((1<<1)<< (
    1<<1)<<(1<<1)<< (1<<1))-((1<<1)<< (1<<1)
    <<(1<<(1>>1)))-((1<<1) <<(1<< (1>>1)))),
    (((1<<1)<< (1<<1)<<(1<<1)<< (1<<1))- ((1
    <<1)<<(1<<1)<<(1<<1))+((1<<1)<< (1<<(1>>
    1)))), (((1<<1)<<(1<<1) <<(1<<1))+(1<<(1
    >>1))),(((1<<1)<<(1<<1))+((1<<1)<< (1<<(
    1>>1))) + (1<< (1>>1)))}; for(i=(1>>1);i
    <(((1<<1) <<(1<<1))+((1 <<1)<< (1<<(1>>1
    ))) + (1<<1)); i++) printf("%c",n[i]); }

这个程序表面上完全不知道在做什么，但实际上就是利用位运算和数组，将字符串 “Hello, World!” 压缩成了一系列整数，最后再打印出来。

将代码编译运行后的结果如下：

Hello, world!

我们来把上面的代码重新格式化过后，再加上详细注释，变成如下代码：

#include <stdio.h>

int main() {
    int i;
    int n[] = {
        (((1<<1)<<(1<<1)<<(1<<1)<<(1<<(1>>1)))+((1<<1)<<(1<<1))),                                       // H
        (((1<<1)<<(1<<1)<<(1<<1)<<(1<<1))-((1<<1)<<(1<<1)<<(1<<1))+((1<<1)<<(1<<(1>>1)))+(1<<(1>>1))),  // e
        (((1<<1)<<(1<<1)<<(1<<1)<<(1<<1))-((1<<1)<<(1<<1)<<(1<<(1>>1)))-((1<<1)<<(1<<(1>>1)))),         // l
        (((1<<1)<<(1<<1)<<(1<<1)<<(1<<1))-((1<<1)<<(1<<1)<<(1<<(1>>1)))-((1<<1)<<(1<<(1>>1)))),         // l
        (((1<<1)<<(1<<1)<<(1<<1)<<(1<<1))-((1<<1)<<(1<<1)<<(1<<(1>>1)))-(1<<(1>>1))),                   // o
        (((1<<1)<<(1<<1)<<(1<<1))+((1<<1)<<(1<<1)<<(1<<(1>>1)))-((1<<1)<<(1<<(1>>1)))),                 // ,
        ((1<<1)<<(1<<1)<<(1<<1)),                                                                       //  
        (((1<<1)<<(1<<1)<<(1<<1)<<(1<<1))-((1<<1)<<(1<<1))-(1<<(1>>1))),                                // w
        (((1<< 1)<<(1<<1)<<(1<<1)<<(1<<1))-((1<<1)<<(1<<1)<<(1<<(1>>1)))-(1<<(1>>1))),                  // o
        (((1<<1)<<(1<<1)<<(1<<1)<<(1<<1))- ((1<<1)<<(1<<1)<<(1<<(1>>1)))+(1<<1)),                       // r
        (((1<<1)<<(1<<1)<<(1<<1)<< (1<<1))-((1<<1)<<(1<<1) <<(1<<(1>>1)))-((1<<1)<<(1<< (1>>1)))),      // l
        (((1<<1)<<(1<<1)<<(1<<1)<< (1<<1))- ((1<<1)<<(1<<1)<<(1<<1))+((1<<1)<< (1<<(1>>1)))),           // d
        (((1<<1)<<(1<<1) <<(1<<1))+(1<<(1>>1))),                                                        // !         
        (((1<<1)<<(1<<1))+((1<<1)<<(1<<(1>>1))) + (1<<(1>>1)))                                          // \r
    }; 
    
    for (i = (1 >> 1); i < (((1 << 1) << (1 << 1)) + ((1 << 1) << (1 << (1 >> 1))) + (1 << 1)); i++) {
        printf("%c",n[i]);
    }
    return 0;
}

现在再看代码就清晰很多了，可以看出是要打印 “Hello, world!” 了。

这代码的可读性非常差，罗列紧凑的位运算难以理解，使用了不寻常的写法，利用了位运算来表示字符的ASCII码，将字符串 “Hello, World!” 压缩成了一系列整数。如果要看懂需要对C语言位运算有一定的熟练度。这代码在技术上是一个有趣的练习，可以展示对位运算和ASCII码的理解。

【参考资料】

6个变态的C语言HELLO WORLD程序

本文链接：https://blog.csdn.net/u012028275/article/details/137424102