C++求两个日期之间的相差天数_c++日期减60天-优快云博客

本文链接：https://blog.youkuaiyun.com/david412306524/article/details/48786075

本文提供了一个使用C++编程语言实现的功能，用于获取指定天数前的日期字符串。通过利用时间戳和日期格式化函数，该代码能够计算并返回给定天数之前的日期。包括日期获取函数和时间戳转换函数。

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参考http://blog.youkuaiyun.com/nanhaizhixin/article/details/8349668

#include <stdio.h>

#include <string>
#include <time.h>

using namespace std;

string GetLastNthDate(int n);
time_t FormatTime2(char * szTime) ;

void main()
{
printf("start!\n");
string timeStr = GetLastNthDate(2);

printf("time:%s", timeStr.c_str());

char time_prev[512] = {0};
sprintf(time_prev,"%s000000","20150905");
char time_curr[512] = {0};
sprintf(time_curr,"%s000000","20150831");
time_t time_t_prev = FormatTime2(time_prev);
time_t time_t_curr = FormatTime2(time_curr);
long long days = (time_t_prev-time_t_curr)/86400; //1天=24*60*60秒

printf("days %lld", days);
}

string GetLastNthDate(int n)
{
time_t current_t = time(0);
time_t lastDay_t = time(0);
char lastDay_time[128];

lastDay_t = current_t - 86400*n; //每天差86400秒
strftime( lastDay_time, sizeof(lastDay_time), "%Y%m%d", gmtime(&lastDay_t));

return string(lastDay_time);
}

time_t FormatTime2(char * szTime)
{
struct tm tm1;
time_t time1;

sscanf(szTime, "%4d%2d%2d%2d%2d%2d",
&tm1.tm_year,
&tm1.tm_mon,
&tm1.tm_mday,
&tm1.tm_hour,
&tm1.tm_min,
&tm1.tm_sec);

tm1.tm_year -= 1900;
tm1.tm_mon --;

tm1.tm_isdst=-1;

time1 = mktime(&tm1);
return time1;
}