The speed of sqlite3 is good Something like echo "select datetime(time,'unixepoch'),id from t1"|sqlite3 0.db Sometimes I need to convert dates in text fil

The speed of sqlite3 is good Something like echo "select datetime(time,'unixepoch'),id from t1"|sqlite3 0.db Sometimes I need to convert dates in text files to or from unixepoch^1 IME, this is at least 2x as slow as converting dates with sqlite3 For example, I have a text file with the following format domainname ipv4-address # unixepoch I use a simple filter something like this ("yy094") /* strftime<-->strptime */ int fileno (FILE *); FILE *f; #define jmp (yy_start)=1+2* #include <time.h> char *strptime(const char *s, const char *f, struct tm *tm); struct tm t; typedef long int time_t; time_t xt; char zt[26]; struct tm *yt; a Mon|Tue|Wed|Thu|Fri|Sat|Sun d (0[1-9]|[12][0-9]|3[01]) b Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec m 0[1-9]|1[012] Y 19[2-9][0-9]|[2-9][0-9]{3} H [0-9]{2} M [0-9]{2} S [0-9]{2} Z [+-][0-9]{2,4}|[A-EG-KMNPSTUWZh]{2,3}[CTAK] int xd70f5083A() { printf("%ld",mktime(&t)); return 0; } int x2146ea7d() { xt=atoi(yytext); if((xt<-2147483646)||(xt>2147483648)) {fwrite(yytext,1,yyleng,yyout);goto s;} yt=localtime(&xt); strftime(zt,sizeof(zt),"%d %b %Y %H:%M:%S %Z",yt); fwrite(zt,sizeof(zt),1,stdout); return 0; s:return 1; } %option nounput noinput noyywrap %% [12][0-9]{9} { x2146ea7d(); } {d}[ ]{b}[ ]{Y}[ ]{H}:{M}:{S}[ ]{Z} { strptime(yytext,"%d %b %Y %H:%M:%S %Z",&t); xd70f5083A(); } {d}[ ]{b}[ ]{Y}[ ]{H}:{M}:{S} { strptime(yytext,"%d %b %Y %H:%M:%S",&t); xd70f5083A(); } {a}[ ]{b}[ ]{d}[ ]{H}:{M}:{S}[ ]UTC[ ]{Y} { strptime(yytext,"%a %b %d %H:%M:%S UTC %Y",&t); xd70f5083A(); } {Y}-{m}-{d}T{H}:{M}:{S} { strptime(yytext,"%Y-%m-%dT%H:%M:%S",&t); xd70f5083A(); } {Y}-{m}-{d}[ ]{H}:{M}:{S} { strptime(yytext,"%Y-%m-%d %H:%M:%S",&t); xd70f5083A(); } .|\n+ fwrite(yytext,1,yyleng,yyout); %% int main(int argc, char *argv[]) { if(argc>1)if(argv[1]) if(argv[1][0]==45) if(argv[1][1]==104) { putc(10,stdout); puts(" usage: yy094 < file"); puts(" zones: UTC only"); puts(" range: 09 Sep 2001 01:46:40 - 19 Jan 2038 03:14:07"); puts(" input formats:"); puts(" 2147483647"); puts(" 09 Sep 2001 01:46:40"); puts(" 09 Sep 2001 01:46:40 UTC"); puts(" 2001 Sep 09 01:46:40"); puts(" 2001-Sep-09T01:46:40"); puts(" 09 Sep 2001 01:46:40 UTC"); puts(" Sun Sep 09 01:46:40 UTC 2001"); puts(" output formats:"); puts(" 19 Jan 2038 03:14:07 UTC"); putc(10,stdout); goto x; } yylex(); x:exit(0); }