num.l

%{
 #include<stdio.h>

 int nums = 0;

%} 

number [0-9]

%%

{number} {nums++; printf("%s", yytext);} 

%%

int yywrap()
{
 return 1;
} 

int main(int argc, char *argv[])
{
 if(argc!=2)
 {
 printf("Usage: <./a.out> <sourcefile>\n");
 exit(0);
 }

 yyin=fopen(argv[1],"r");
 
 yylex();

 printf("\nNumbers = %d\n",nums);
 
 return 0;

}