C++标准C函数在各平台编译结果都相同

#include <stdio.h>
#include <stdlib.h>
int main()
{
 for (int i=0; i<10; i++)
 {
 printf("%d\n", rand()%100);
 }
}

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
int main()
{
 srand(time(NULL));
 for (int i=0; i<10; i++)
 {
 printf("%d\n", rand()%100);
 }
}

#include <stdio.h>
#include <time.h>
int main()
{
 time_t ts = time(NULL);
 printf("%d\n", (int)ts);
}

#include <stdio.h>
#include <time.h>
int main()
{
 time_t ts = time(NULL);
 tm time = *localtime(&ts);
 int year = time.tm_year + 1900;
 int month = time.tm_mon + 1;
 int day = time.tm_mday;
  int hour = time.tm_hour;
 int min = time.tm_min;
 int sec = time.tm_sec;
 int week = time.tm_wday ;
 return 1;
}

#include <stdio.h>
#include <time.h>
int main()
{
 //时间为2017-07-15 21:38:30
 tm time = {0};
 time.tm_year = 2017 - 1900;
 time.tm_mon = 7 -1;
 time.tm_mday = 15;
  time.tm_hour = 21;
 time.tm_min = 38;
 time.tm_sec = 30;
 time_t ts = mktime(&time);
 //获得该天为周几
 tm time1 = *localtime(&ts);
 printf("周%d\n", time1.tm_wday);
 return 1;
}