#define _XOPEN_SOURCE #include <stdio.h> #include <time.h> #include <string.h> .... struct tm time1,time2; memset(&time1,0x0,sizeof(struct tm)); memset(&time2,0x0,sizeof(struct tm)); strptime((*requesttokens)[i][5]->str,"%Y-%m-%d %H:%M:%S",&time1); strptime((*requesttokens)[i][5]->str,"%Y-%m-%d %H:%M:%S",&time2); printf("compared time: %ld %ld\n",(long)mktime(&time1),(long)mktime(&time2));