Flex&Bison: Using flex on OSX 在mac上使用Flex

一个简单的示例：文件名fb1-1.l (一杠一 后缀字母L)

%{
int chars = 0;
int words = 0;
int lines = 0;
%}

%%

[a-zA-Z]+ {words++; chars += strlen(yytext);}
\n  { chars++; lines++; }
.  { chars++; }

%%

int main(int argc, char **argv){
   yylex();
   printf("%8d%8d%8d\n", lines, words, chars);
}

在终端输入以下命令：

flex fb1-1.l  //generates a new file named "lex.yy.c"

/*
this action would generate a file named a.out which would be used for reading inputs and print outputs
*/
cc lex.yy.c -ll  //如果不是在mac上，是用参数-lfl

./a.out  //run the file and type in inputs from your command line

在终端输入一段文字，按control 加 D结束即可看到输出