[英]add delay to time format struct “tm”
我想在格式struct“tm”中添加延遲,所以我運行此代碼:
#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#include<limits.h>
#define SEC_PER_DAY 86400
#define SEC_PER_HR 3600
#define SEC_PER_MIN 60
int main(void) {
time_t now;
time_t time_delay;
struct tm *ts;
struct tm *ts_delay;
char buf[140];
char buf_delay[140];
now = time(NULL);
int delay =100;
ts_delay = localtime(&now);
printf("day = %d \n",ts_delay->tm_mday);
ts_delay->tm_mday += delay /SEC_PER_DAY;
printf("day = %d \n",ts_delay->tm_mday);
printf("hour = %d \n",ts_delay->tm_hour);
ts_delay->tm_hour += (delay%SEC_PER_DAY)/SEC_PER_HR;
printf("hour = %d \n",ts_delay->tm_hour);
printf("min = %d \n",ts_delay->tm_min);
ts_delay->tm_min += ((delay%SEC_PER_DAY)%SEC_PER_HR)/SEC_PER_MIN;
printf("min = %d \n",ts_delay->tm_min);
printf("sec = %d \n",ts_delay->tm_sec);
ts_delay->tm_sec += ((delay%SEC_PER_DAY)%SEC_PER_HR)%SEC_PER_MIN;
printf("sec = %d \n",ts_delay->tm_sec);
/* Format and print the time, "ddd yyyy-mm-dd hh:mm:ss zzz" */
ts = localtime(&now);
strftime(buf, sizeof(buf), "%FT%T%z", ts);
strftime(buf_delay, sizeof(buf_delay), "%FT%T%z", ts_delay);
puts(buf);
puts(buf_delay);
return 0;
}
結果 :
day = 6
day = 6
hour = 4
hour = 4
min = 14
min = 15
sec = 24
sec = 64
2013-12-06T04:14:24-0600 ==> ts
2013-12-06T04:14:24-0600 ==> ts_delay
似乎延遲沒有添加到ts_delay !!
任何推向正確的方向都會非常有幫助
你的struct tm * ts_delay
會被2.對localtime()
調用覆蓋你有這樣的代碼:
ts_delay = localtime(&now);
... change ts_delay;
ts = localtime(&now);
現在, localtime()
返回一個指針。 因此必須分配一些存儲,以便localtime的返回值可以指向somwhere有效。 運行時將在單個靜態緩沖區(可能是每個線程)中將該存儲分配給localtime()的結果。 因此2.調用localtime()將覆蓋ts_delay
指向的相同緩沖區。
而是將localtime()的結果復制到您自己管理的存儲中,而不是將struct tm
指針用於單個可用緩沖區。
struct tm ts; //not a pointer anymore
struct tm ts_delay;
ts_delay = *localtime(&now); //copy the returned struct
... change ts_delay;
ts = *localtime(&now);
或者如果你的平台提供它,請使用getlocaltime_r
,例如
localtime_r(&now, &ts);
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