cedarz · February 28, 2024 09:13 · Feb 28, 2024 · Nov 30, 2020 · Nov 27, 2020 · Nov 27, 2020
diff --git a/timer.cpp b/timer.cpp
@@ -0,0 +1,18 @@
+class ScopedTimer
+{
+public:
+    ScopedTimer(const std::string& name = "ScopeTimer") : eventName(name)
+    {
+        start = std::chrono::system_clock::now();
+    }
+
+    ~ScopedTimer()
+    {
+        auto end = std::chrono::system_clock::now();
+        std::cout << eventName << " : " << std::chrono::duration_cast<std::chrono::milliseconds>(end - start).count() << "ms" << std::endl;
+    }
+
+private:
+    std::string eventName;
+    std::chrono::system_clock::time_point start;
+};
diff --git a/[ Example ] C++ run time → chrono_gettime.cpp b/[ Example ] C++ run time → chrono_gettime.cpp
diff --git a/[ Example ] clock_gettime → clock_gettime.cpp b/[ Example ] clock_gettime → clock_gettime.cpp
diff --git a/Test one function's run time. → clock_gettime_example.cpp b/Test one function's run time. → clock_gettime_example.cpp
diff --git a/Test one function's run time. b/Test one function's run time.
@@ -1,16 +1,21 @@
-struct timespec start, end;
-clock_gettime(CLOCK_MONOTONIC, &start);
+#include <time.h>
 
-// test...
+int main(void)
+{
+  struct timespec start, end;
+  clock_gettime(CLOCK_MONOTONIC, &start);
 
-clock_gettime(CLOCK_MONOTONIC, &end);
+  // test...
 
-// print
-// Calculating total time taken by the program.
-double time_taken;
-time_taken = (end.tv_sec - start.tv_sec) * 1e9;
-time_taken = (time_taken + (end.tv_nsec - start.tv_nsec)) * 1e-9;
+  clock_gettime(CLOCK_MONOTONIC, &end);
 
-cout << "Time taken by program is : " << fixed << setprecision(9)
-     << time_taken;
-cout << " sec" << endl;
+  // print
+  // Calculating total time taken by the program.
+  double time_taken;
+  time_taken = (end.tv_sec - start.tv_sec) * 1e9;
+  time_taken = (time_taken + (end.tv_nsec - start.tv_nsec)) * 1e-9;
+
+  cout << "Time taken by program is : " << fixed << setprecision(9)
+      << time_taken;
+  cout << " sec" << endl;
+}
diff --git a/[ Example ] C++ run time b/[ Example ] C++ run time
@@ -1,21 +1,29 @@
-// unsync the I/O of C and C++.
-ios_base::sync_with_stdio(false);
+#include <iostream>
+#include <chrono>
 
-// auto start = chrono::system_clock::now();
-auto start = chrono::steady_clock::now();
+using namespace std;
 
-func();
+int main(void)
+{
+  // unsync the I/O of C and C++.
+  ios_base::sync_with_stdio(false);
 
-// please do not use high_resolution_clock. see: https://zh.cppreference.com/w/cpp/chrono/high_resolution_clock
-// auto end = chrono::system_clock::now();
-auto end = chrono::steady_clock::now();
+  // auto start = chrono::system_clock::now();
+  auto start = chrono::steady_clock::now();
 
-// Calculating total time taken by the program.
-double time_taken
-        = chrono::duration_cast<chrono::nanoseconds>(end - start).count();
+  func();
 
-time_taken *= 1e-9;
+  // please do not use high_resolution_clock. see: https://zh.cppreference.com/w/cpp/chrono/high_resolution_clock
+  // auto end = chrono::system_clock::now();
+  auto end = chrono::steady_clock::now();
 
-cout << "Time taken by program is : " << fixed << setprecision(9)
-     << time_taken;
-cout << " sec" << endl;
+  // Calculating total time taken by the program.
+  double time_taken
+          = chrono::duration_cast<chrono::nanoseconds>(end - start).count();
+
+  time_taken *= 1e-9;
+
+  cout << "Time taken by program is : " << fixed << setprecision(9)
+       << time_taken;
+  cout << " sec" << endl;
+}
diff --git a/[ Example ] C++ run time b/[ Example ] C++ run time
@@ -0,0 +1,21 @@
+// unsync the I/O of C and C++.
+ios_base::sync_with_stdio(false);
+
+// auto start = chrono::system_clock::now();
+auto start = chrono::steady_clock::now();
+
+func();
+
+// please do not use high_resolution_clock. see: https://zh.cppreference.com/w/cpp/chrono/high_resolution_clock
+// auto end = chrono::system_clock::now();
+auto end = chrono::steady_clock::now();
+
+// Calculating total time taken by the program.
+double time_taken
+        = chrono::duration_cast<chrono::nanoseconds>(end - start).count();
+
+time_taken *= 1e-9;
+
+cout << "Time taken by program is : " << fixed << setprecision(9)
+     << time_taken;
+cout << " sec" << endl;
diff --git a/Test one function's run time. b/Test one function's run time.
@@ -0,0 +1,16 @@
+struct timespec start, end;
+clock_gettime(CLOCK_MONOTONIC, &start);
+
+// test...
+
+clock_gettime(CLOCK_MONOTONIC, &end);
+
+// print
+// Calculating total time taken by the program.
+double time_taken;
+time_taken = (end.tv_sec - start.tv_sec) * 1e9;
+time_taken = (time_taken + (end.tv_nsec - start.tv_nsec)) * 1e-9;
+
+cout << "Time taken by program is : " << fixed << setprecision(9)
+     << time_taken;
+cout << " sec" << endl;
diff --git a/[ Example ] clock_gettime b/[ Example ] clock_gettime
@@ -0,0 +1,41 @@
+/* int clock_gettime( clockid_t clock_id, struct
+   timespec *tp ); The clock_gettime() function gets
+   the current time of the clock specified by clock_id,
+   and puts it into the buffer  pointed to by tp.tp
+   parameter points to a structure containing
+   atleast the following members:
+   struct timespec {
+             time_t   tv_sec;        // seconds
+             long     tv_nsec;       // nanoseconds
+         };
+  clock id = CLOCK_REALTIME, CLOCK_PROCESS_CPUTIME_ID,
+             CLOCK_MONOTONIC ...etc
+  CLOCK_REALTIME : clock  that  measures real (i.e., wall-clock) time.
+  CLOCK_PROCESS_CPUTIME_ID : High-resolution per-process timer
+                             from the CPU.
+  CLOCK_MONOTONIC : High resolution timer that is unaffected
+                    by system date changes (e.g. NTP daemons).  */
+  struct timespec start, end;
+
+  // start timer.
+  // clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start);
+  // clock_gettime(CLOCK_REALTIME, &start);
+  clock_gettime(CLOCK_MONOTONIC, &start);
+
+  // unsync the I/O of C and C++.
+  ios_base::sync_with_stdio(false);
+
+  func();
+  // stop timer.
+  // clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end);
+  // clock_gettime(CLOCK_REALTIME, &end);
+  clock_gettime(CLOCK_MONOTONIC, &end);
+
+  // Calculating total time taken by the program.
+  double time_taken;
+  time_taken = (end.tv_sec - start.tv_sec) * 1e9;
+  time_taken = (time_taken + (end.tv_nsec - start.tv_nsec)) * 1e-9;
+
+  cout << "Time taken by program is : " << fixed << setprecision(9)
+       << time_taken;
+  cout << " sec" << endl;
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