如何比较两个时间标记的格式和QUOT;当月日期hh：mm：ss的＆QUOT;检查+ ve或-ve值 [英] How to compare two time stamp in format "Month Date hh:mm:ss" to check +ve or -ve value

问题描述

我检查我的回答对计算器的网站，我没有得到，所以我在这里张贴。

I checked the stackoverflow site for my answer, i did not get, so i am posting it here.

我的问题是：

如何比较格式两个时间戳记月日HH：MM：SS？

How to compare two time stamp in format "Month Date hh:mm:ss"?

我写在C和C ++程序和时间是显示的字符串格式。

I am writing program in C and C++ and the time is in displayable string format.

例如：

time1 = "Mar 21 11:51:20"
time2 = "Mar 21 10:20:05"

我想比较时间1和tme2并找出时间2 是的之后的时间1 与否，我需要为输出真正或假，象下面这样：

I want to compare time1 and tme2 and find out whether time2 is after time1 or not and I need output as true or false, like below:

 if time2 > time1 then 
       i need output as 1 
 or 
       0 or -1 anything

我用 difftime（时间2，时间1），但它返回的时间增量差异 <$ C $之间C>时间1 和时间2 。结果
我要检查更大与否。

I used difftime(time2,time1) , but it returns the delta time diff between time1 and time2.
I want to check greater or not.

有关任何帮助，在此先感谢

For any help, thanks in advance

推荐答案

FIRST - 使用difftime进行比较：

FIRST- use difftime to compare:

您可以简单地使用 difftime（） 功能比较时，返回 1 或 1 如下：

you can simply use difftime() function to compare time and return 1 or -1 as follows:

int comparetime(time_t time1,time_t time2){
 return difftime(time1,time2) > 0.0 ? 1 : -1; 
} 

第二 - 转换成字符串时间：

如果您有困难的转换 字符串 到 time_t的结构，可以按顺序使用两个功能：

If you have difficulty to convert string into time_t struct, you can use two functions in sequence:

1. 的char * strptime（为const char * buf中，为const char *格式，结构TM * TM）; 功能。字符串转换成结构TM

例如：转换时间串3月21日上午十一时51分20秒到结构TM 需要三个甲字符串：

Example: to convert date-time string "Mar 21 11:51:20 AM" into struct tm you need three formate strings:

％B ：月份名称，可以是全名或缩写结果
  ％d个：月[1-31]​​日结果
  ％R ：时间在现场的AM / PM格式。如果区域设置时间格式不可用，默认为POSIX时间AM / PM格式：％I：％M：％S％P

%b : Month name, can be either the full name or an abbreviation
%d : Day of the month [1–31].
%r : Time in AM/PM format of the locale. If not available in the locale time format, defaults to the POSIX time AM/PM format: %I:%M:%S %p.

time_t的mktime（结构TM * timeptr）; 功能转换结构TM * 到 time_t的

下面是我的示例程序：

#include <stdio.h>
#include <time.h>
int main(void){
    time_t t1, t2;
    struct tm *timeptr,tm1, tm2;
    char* time1 = "Mar 21 11:51:20 AM";
    char* time2 = "Mar 21 10:20:05 AM";

    //(1) convert `String to tm`:  
    if(strptime(time1, "%b %d %r",&tm1) == NULL)
            printf("\nstrptime failed\n");          
    if(strptime(time2, "%b %d %r",&tm2) == NULL)
            printf("\nstrptime failed\n");

    //(2)   convert `tm to time_t`:    
    t1 = mktime(&tm1);
    t2 = mktime(&tm2);  

     printf("\n t1 > t2 : %d", comparetime(t1, t2));
     printf("\n t2 > t1 : %d", comparetime(t2, t1));
     printf("\n");
     return 1;
}

和它的作品，你的愿望：

And it works as you desire:

 $ ./a.out 
 t1 > t2 : 1
 t2 > t1 : -1

要计算两个日期之间的区别如下：<一href=\"http://stackoverflow.com/questions/21862808/how-do-you-find-the-difference-between-two-dates-in-hours-in-c/21864664#21864664\">How你觉得以小时为单位的两个日期之间的差别，在C？

To calculate difference between two dates read: How do you find the difference between two dates in hours, in C?

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