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std::difftime

From cppreference.com
< cpp‎ | chrono‎ | c
 
 
Date and time library
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C-style date and time utilities
Functions
Time manipulation
difftime
(C++17)
Format conversions
Constants
Types
(C++17)
 
Defined in header <ctime>
double difftime( std::time_t time_end, std::time_t time_beg );

Computes difference between two calendar times as std::time_t objects (time_end - time_beg) in seconds. If time_end refers to time point before time_beg then the result is negative.

[edit] Parameters

time_beg, time_end - times to compare

[edit] Return value

Difference between two times in seconds.

[edit] Notes

On POSIX systems, std::time_t is measured in seconds, and difftime is equivalent to arithmetic subtraction, but C and C++ allow fractional units for time_t.

[edit] Example

Run this code
#include <ctime>
#include <iostream>
 
int main()
{
 std::time_t start = std::time (nullptr);
 volatile double d = 1.0;
 
 // some time-consuming operation
 for (int p = 0; p < 10000; ++p)
 for (int q = 0; q < 100000; ++q)
 d = d + p * d * q + d;
 
 std::cout << "Wall time passed: "
 << std::difftime(std::time (nullptr), start) << " s.\n";
}

Possible output:

Wall time passed: 9 s.

[edit] See also

(C++11)
a time interval
(class template) [edit]
C documentation for difftime
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