Thread: Function not returning date string

Code:

#include<stdio.h>
#include<time.h>
#include<stdlib.h>
#include<string.h>

void date(char *);

int main(void)
{
    char dtstr[11];
    date(dtstr);
    puts(dtstr);
    return 0;
}

void date(char *)
{
    int day, month, year;
    time_t now;
    time(&now);
    struct tm *local = localtime(&now);
    day = local->tm_mday;        
    month = local->tm_mon + 1;       
    year = local->tm_year + 1900;    

    char dtstr[11];

    char d[2];
    sprintf(d,"%d",day);
            
    char m[2];
    sprintf(m,"%d",month);
    
    char y[4];
    sprintf(y,"%d",year);

    strcat(dtstr,d);
    strcat(dtstr,"/");
    strcat(dtstr,m);
    strcat(dtstr,"/");
    strcat(dtstr,y);
//    puts(dtstr);
}

Why is dtstr not available for printing in main()?