C - Segmentation fault with strtok() -

C - Segmentation fault with strtok() -

i trying date console , getting month, day , year work them separately.

const size_t max = 11; void getdate(date * d){ char line[max]; printf("\t insert date in american format (mm/dd/yyyy): "); fgets(line, max, stdin); d->month = atoi(strtok(line, "/")); d->day = atoi(strtok(null, "/")); d->year = atoi(strtok(null, " ")); }

i don't error executing once. segmentation fault error when seek 2 dates @ once.

date d1, d2; getdate(&d1); getdate(&d2);

and line gives me error d->day = atoi(strtok(null, "/")); during sec execution.

the problem utilize of fgets(). not returning think sec time around.

the first time through, fgets() fills line[] "10/23/2014\0" , well.

however, sec time through, enter key still in stdin's input buffer because first fgets() did not have room in line[] read it, sec fgets() fills line[] "\n\0" without waiting new user input. first phone call strtok(line, "/") returns "\n" (which atoi() converts 0), next phone call strtok(null, "/") fails , returns null, causes atoi() segfault.

increase size of array enter read each phone call fgets(). suggest utilize sscanf() instead of atoi(strtok()):

const size_t max = 16; void getdate(date * d) { char line[max]; printf("\t insert date in american format (mm/dd/yyyy): "); fgets(line, max, stdin); if (sscanf(line, "%d/%d/%d", &(d->month), &(d->day), &(d->year)) != 3) d->month = d->day = d->year = 0; }

alternatively, add together validation create sure date read properly:

const size_t max = 16; void getdate(date * d) { char line[max]; int consumed; printf("\t insert date in american format (mm/dd/yyyy): "); fgets(line, max, stdin); while (1) { if (sscanf(line, "%d/%d/%d%n", &(d->month), &(d->day), &(d->year), &consumed) == 3) { if (consumed == strlen(line)) break; } printf("\t invalid input. insert date in american format (mm/dd/yyyy): "); fgets(line, max, stdin); } }

c strtok