How to pass a variable between function without loose any data

I have a big problem, i have build a code where I catch rtc data and pass it to a string , with this I made the name of the file, based in year/month/day/hour/minuts/seconds. This way I assure there is no way to have two files with same name.
Based in this spintf convertion I send it to another page where I try to creat the file , but something goes wrong because this string does not arrive full.
example:

file1.c

char dateAndTimeFile[];
void setUserDefinedTime(int rtc_year, int rtc_month, int rtc_day, int rtc_hour, int rtc_minute, int rtc_second){
    /*CONVERT INTO SINGLE EXPRESSION FOR TIME FILE*/
     sprintf(dateAndTimeFile,"HealthFile20%02d%02d%02d%02d%02d%02dLOG.txt",
     rtc_year, rtc_month, rtc_day, rtc_hour, rtc_minute, rtc_second);
     setParameterCreateInputFile(dateAndTimeFile);
}

file2.c

char *inputfile;
void setParameterCreateInputFile(char str[]){
    inputfile = str;
    printf("file:%s\n", (TCHAR*)inputfile);

// all FULL string present
SDCARD_Open();
}

void SDCARD_Open(void){
printf("LOAD %s\n", (TCHAR*)inputfile);
//this code appear to be broken only show LOAD Heal
}

You must make the array dateAndTimeFile large enough to store the string written by sprintf.

In the line

char dateAndTimeFile[];

you are not specifying the size of the array, so it is not guaranteed that the size is sufficient.

The string that sprintf writes will have a length of at least 31 characters (32 including the null terminating character). Depending on the value of the integer arguments, the length may be larger.

Therefore, you must make the size of the array at least 32 bytes, like this:

char dateAndTimeFile[32];

However, unless you are on a platform with very little memory, it would probably be better to be generous, for example to set the size of the array to 100 or 200 bytes. Otherwise, you will risk a buffer overflow.

For additional safety, I suggest that you use the function snprintf instead of sprintf. That way, a buffer overflow cannot occur, even in cases in which the string ends up being significantly longer than intended.

Instead of

sprintf(dateAndTimeFile,"HealthFile20%02d%02d%02d%02d%02d%02dLOG.txt",
     rtc_year, rtc_month, rtc_day, rtc_hour, rtc_minute, rtc_second);

I suggest that you write:

int wants_to_write = snprintf(
    dateAndTimeFile, sizeof dateAndTimeFile,
    "HealthFile20%02d%02d%02d%02d%02d%02dLOG.txt",
    rtc_year, rtc_month, rtc_day,
    rtc_hour, rtc_minute, rtc_second
);
if ( wants_to_write < 0 || wants_to_write >= sizeof dateAndTimeFile )
{
    fprintf( stderr, "Error writing to buffer!\n" );
    exit( EXIT_FAILURE );
}

That way, your program will print an error message if the buffer is not large enough, instead of overflowing the buffer (which may cause the program to crash).