difftime
From cppreference.com
| Defined in header <time.h>
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Computes difference between two calendar times as time_t objects (time_end - time_beg) in seconds. If time_end refers to time point before time_beg then the result is negative.
Parameters
| time_beg, time_end | - | times to compare |
Return value
Difference between two times in seconds.
Notes
On POSIX systems, time_t is measured in seconds, and difftime is equivalent to arithmetic subtraction, but C and C++ allow fractional units for time_t.
Example
The following program computes the number of seconds that have passed since the beginning of the month.
Run this code
#include <stdio.h> #include <time.h> int main(void) { time_t now = time(0); struct tm beg = *localtime(&now); // set beg to the beginning of the month beg.tm_hour = 0, beg.tm_min = 0, beg.tm_sec = 0, beg.tm_mday = 1; double seconds = difftime(now, mktime(&beg)); printf("%.f seconds have passed since the beginning of the month.\n", seconds); return 0; }
Output:
1937968 seconds have passed since the beginning of the month.
References
- C17 standard (ISO/IEC 9899:2018):
- 7.27.2.2 The difftime function (p: 285)
- C11 standard (ISO/IEC 9899:2011):
- 7.27.2.2 The difftime function (p: 390)
- C99 standard (ISO/IEC 9899:1999):
- 7.23.2.2 The difftime function (p: 338)
- C89/C90 standard (ISO/IEC 9899:1990):
- 7.12.2.2 The difftime function (p: 171)
See also
| C++ documentation for difftime
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