你也许听说过“国际C 语言乱码大赛(IOCCC )”，能获奖的人毫无疑问是世界顶级C 程序员。这是他们利用C 语言的特点极限挖掘的结果。下面这个例子就是网上广为流传的 一个经典作品：// 原始代码如下

#include  char *a;main(int t,int _,char* a){return!0

这是IOCCC 1988 年获奖作品，作者是Ian Phillipps。 毫无疑问，Ian Phillipps 是世界上最顶级的C 语言程序员之一。你可以数数这里面用了多少个符号。当然这里我并不会讨论这段代码，也并不是鼓励你也去写这样的代码(关于这段代码的分析，你可以上网查询)。恰恰相反，我要告诉你的是： 大师把代码写成这样是经典，你把代码写成这样是垃圾！所以在垃圾和经典之间，你需要做一个抉择。

// 把代码格式化一下#include  char *a; // can be omitted due to function fieldmain(int t,int _,char* a){return !0

// 翻译成常规语言// condition ? true : false ; a,b,c generate step#include  main(int t,int _,char* a){// 逻辑运算优先级，便于理解if(!0

// 除去不需要的，重构if语句#include  main(int t,int _,char* a){if(1

// 编译环境main入口，CRTO.C for main(__argc, __argv, _environ);// 方法的编译原来，返回值的寄存器状态// 变量的类型转换reinterpret_cast// 使用一个新的main方法，将旧的用一个新方法'decode'表示// 根据题设，本程序执行方式为无命令参数，即，argc==1// 变量的声名规约，改变变量名以方便理解// 进一步重构if语句#include  int decode(int arg1,int arg2,char* sCodec){if(1

// 分析出递归顶层返回值。// 注意所有return的含义，9/16/1/putchar()，Non Zero -> TRUE// 分析arg1的内容，重构方法，有些坳，自己试着理解吧#include  int decode(int arg1,int arg2,char* sCodec){if(1

decode(-27+arg1,-94,"@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l+,/n{n+,/+#n+,/#;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l q#'+d'K#!/+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# ){nl]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#n'wk nw' iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c ;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;#'rdq#w! nr'/ ') }+}{rl#'{n' ')# }'+}##(!!/");    }   }}else if(arg1

// 分析条件，重构2#include  int decode(int arg1,int arg2,char* sCodec){if(1

// arg1 <= 0，下同   decode(-27+arg1,-94,"@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l+,/n{n+,/+#n+,/#;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l q#'+d'K#!/+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# ){nl]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#n'wk nw' iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c ;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;#'rdq#w! nr'/ ') }+}{rl#'{n' ')# }'+}##(!!/");   if(arg1==2){    while(arg2<13){     arg2 ++;     sCodec = "%s %d %d\n";     if(arg1<3){      decode(0,-86,"@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l+,/n{n+,/+#n+,/#;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l q#'+d'K#!/+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# ){nl]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#n'wk nw' iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c ;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;#'rdq#w! nr'/ ') }+}{rl#'{n' ')# }'+}##(!!/");      decode(1-arg2,-87,"@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l+,/n{n+,/+#n+,/#;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l q#'+d'K#!/+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# ){nl]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#n'wk nw' iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c ;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;#'rdq#w! nr'/ ') }+}{rl#'{n' ')# }'+}##(!!/");      decode(-13,-79,"@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l+,/n{n+,/+#n+,/#;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l q#'+d'K#!/+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# ){nl]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#n'wk nw' iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c ;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;#'rdq#w! nr'/ ') }+}{rl#'{n' ')# }'+}##(!!/");     }     if(arg1

decode(-27+arg1,-94,"@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l+,/n{n+,/+#n+,/#;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l q#'+d'K#!/+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# ){nl]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#n'wk nw' iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c ;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;#'rdq#w! nr'/ ') }+}{rl#'{n' ')# }'+}##(!!/");    }   }}else if(arg1<=0){    // 单一条件代码组   int border = (arg1<0);   for(;arg1<0;arg1+=(*sCodec=='/'))    sCodec ++;   if(border)    sCodec ++; // 边界条件，注意   while(!(*sCodec=='/')){    char* s = "!ek;dc i@bK'(q)-[w]*%n+r3#l,{}:\nuwloca-O;m .vpbks,fxntdCeghiry";    while(!(*sCodec==*s)){     s ++;    }    putchar(s[31]);    sCodec ++;   }}return 1;}int main(int argc, char* argv[], char** _environ){decode(2,2,"%s");return 9;}

// 分析arg2代码流向，重构3// tip.arg1 in function decode always '> 1'// the usage of arg1, arg2, sCodec. Can be omitted.#include  void decode2(int arg1){char* sCodec = "@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l+,/n{n+,/+#n+,/#;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l q#'+d'K#!/+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# ){nl]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#n'wk nw' iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c ;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;#'rdq#w! nr'/ ') }+}{rl#'{n' ')# }'+}##(!!/";int border = (arg1<0);for(;arg1<0;arg1+=(*sCodec=='/'))   sCodec ++;if(border)   sCodec ++; while(!(*sCodec=='/')){   char* s = "!ek;dc i@bK'(q)-[w]*%n+r3#l,{}:\nuwloca-O;m .vpbks,fxntdCeghiry";   while(!(*sCodec==*s)){    s ++;   }   putchar(s[31]);   sCodec ++;}}int decode(int arg1,int arg2){// 考虑初始条件的 arg1 == 2, arg2 == 2，代码合并// 内部递归，展平为递推方式，注意边界条件和递归嵌套的调用特点if(arg1<3){   decode2(0);   decode2(1-arg2);   decode2(-13);}if(arg1

decode2(-27+arg1);if(arg1==2){   while(arg2<13){    arg2 ++;    if(arg1<3){     decode2(0);     decode2(1-arg2);     decode2(-13);    }    if(arg1

decode2(-27+arg1);   }}return 1;}int main(int argc, char* argv[], char** _environ){decode(2,2);return 9;}

// 最终结果#include  void decode2(int arg1){char* sCodec = "@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l+,/n{n+,/+#n+,/#;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l q#'+d'K#!/+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# ){nl]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#n'wk nw' iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c ;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;#'rdq#w! nr'/ ') }+}{rl#'{n' ')# }'+}##(!!/";int border = (arg1<0);for(;arg1<0;arg1+=(*sCodec=='/'))   sCodec ++;if(border)   sCodec ++; while(!(*sCodec=='/')){   char* s = "!ek;dc i@bK'(q)-[w]*%n+r3#l,{}:\nuwloca-O;m .vpbks,fxntdCeghiry";   while(!(*sCodec==*s)){    s ++;   }   putchar(s[31]);   sCodec ++;}}int decode(){int arg1, arg2;for(arg2=2;arg2<=13;arg2++){   decode2(0);   decode2(1-arg2);   decode2(-13);

for(arg1=arg2;arg1>=2;arg1--)    decode2(-27+arg1);}return 1;}int main(int argc, char* argv[], char** _environ){decode();return 9;}

// 额外写段代码，看一下。对照之后推一下原始代码的结果吧。#include  int main(int argc, char* argv[], char** _environ){char a[]="@n'+,#'/*{}w+/w#cdnr/+,{}r/*de}+,/*{*+,/w{%+,/w#q#n+,/#{l+,/n{n+,/+#n+,/#;#q#n+,/+k#;*+,/'r :'d*'3,}{w+K w'K:'+}e#';dq#'l q#'+d'K#!/+k#;q#'r}eKK#}w'r}eKK{nl]'/#;#q#n'){)#}w'){){nl]'/+#n';d}rw' i;# ){nl]!/n{n#'; r{#w'r nc{nl]'/#{l,+'K {rw' iK{;[{nl]'/w#q#n'wk nw' iwk{KK{nl]!/w{%'l##w#' i; :{nl]'/*{q#'ld;r'}{nlwb!/*de}'c ;;{nl'-{}rw]'/+,}##'*}#nc,',#nw]'/+kd'+e}+;#'rdq#w! nr'/ ') }+}{rl#'{n' ')# }'+}##(!!/";char b[]="!ek;dc i@bK'(q)-[w]*%n+r3#l,{}:\nuwloca-O;m .vpbks,fxntdCeghiry";for(int i=0;i