CODEWITHSUNDEEP
c
JohnnyF
JohnnyF

Reputation: 1101

Add date and time to a file name in c

Im looking for a way to add the current date and time to a log file im opening for now im using :

fopen("/var/log/SA_TEST","w");

How to make it

fopen("/var/log/SA_TEST_DATE_AND_TIME","w");

Thx a lot (In c)

Upvotes: 9

Views: 23305

Answers (5)

warazdr
warazdr

Reputation: 1

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

int main(int argc, char* argv[]) {

    printf("Runfile: %s Date: %s Time : %s \n", __FILE__, __DATE__, __TIME__ );

    FILE     *fptr;
    char     *fmode, filename[255], strtime_sec[20], strtime_nsec[20];
    struct   tm* tm;            
    struct   timespec ts;
    time_t   now;

    now = time(NULL);          // get current time
    tm  = localtime(&now);     // get time structure

    // Get current time from system clock    
    clock_gettime(CLOCK_REALTIME, &ts);

    // Convert integer times to strings using snprintf()
    snprintf(strtime_sec,  20, "%d",  ts.tv_sec);
    snprintf(strtime_nsec, 20, "%ld", ts.tv_nsec);

    // Generate dynamic filename and set filemode
    sprintf(filename, "file_%04d%02d%02d_%s.txt", tm->tm_year+1900, tm->tm_mon+1, tm->tm_mday, strtime_sec);
    fmode = "a";       

    // Open file and write some text into the file
    fptr = fopen(filename, fmode);
    if (fptr == NULL) { 
        printf("Cannot open filename \n"); 
        exit(0); 
    } 

    // Test by writing text into the file stream using fprintf()
    fprintf(fptr, "# Runfile: %s Date: %s Time : %s \n", __FILE__, __DATE__, __TIME__ );

    int i; double value, result;
    value = 0.5; 
    for(i = 0; i < 10; i++) {
       result = value/5.5;
       fprintf(fptr, "%d \t %f \t %f \n", i, value, result);
       value = value * 2.5;
    }
    fclose(fptr);

return(0);
}

Upvotes: 0

Ek1noX
Ek1noX

Reputation: 493

strftime can be used to format the date an time : 

#include <time.h>

char filename[40];
struct tm *timenow;

time_t now = time(NULL);
timenow = gmtime(&now);

strftime(filename, sizeof(filename), "/var/log/SA_TEST_%Y-%m-%d_%H:%M:%S", timenow);

fopen(filename,"w");

You can change the date an time format for whatever you want according to the strftime manual.

You can use the timestamp as 'compact format' with the result of time only.

sprintf(filename, "/var/log/SA_TEST_%d", (int)now);

Upvotes: 13

askmish
askmish

Reputation: 6674

  time_t rawtime;
  struct tm * timeinfo;
  char buffer [64];

  time (&rawtime);
  timeinfo = localtime (&rawtime);

  strftime (buffer,64,"/var/log/SA_TEST_%x_%X",timeinfo);//generate string SA_TEST_DATE_TIME
  fopen(buffer, "w");

Refer: man strftime for the formats you can get time and date in.

Upvotes: 3

Jeegar Patel
Jeegar Patel

Reputation: 27210

/* ctime example */
#include <stdio.h>      /* printf */
#include <time.h>       /* time_t, time, ctime */

int main ()
{
  time_t rawtime;
  char buffer [255];

  time (&rawtime);
  sprintf(buffer,"/var/log/SA_TEST_%s",ctime(&rawtime) );
// Lets convert space to _ in

char *p = buffer;
for (; *p; ++p)
{
    if (*p == ' ')
          *p = '_';
}



  printf("%s",buffer);
  fopen(buffer,"w");

  return 0;
}

Output is 

/var/log/SA_TEST_Wed_Jul_30_12:17:19_2014

Upvotes: 7

prince
prince

Reputation: 1149

Use sprintf in following way

char date_time[30];   //Collect system date and time in this character array
char filename[40]
sprintf(filename, "/var/log/SA_TEST_%s", date_time);
fopen(filename,"w");

Upvotes: 1

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