void retrieveTime5(char *dtValue); void showTime6(); void passFunc(void(*funcName)()); int main() { passFunc(&showTime6); return 0; } void passFunc(void(*funcName)()) { chrono::time_point<chrono::system_clock> startTime; chrono::time_point<chrono::system_clock> endTime; startTime=chrono::system_clock::now(); printf("Started in passFunc!n"); (*funcName)(); endTime=chrono::system_clock::now(); printf("Ended in passFunc!n"); cout<<"Time cost:" <<chrono::duration_cast<chrono::seconds>(endTime-startTime).count()<<" seconds," <<chrono::duration_cast<chrono::milliseconds>(endTime-startTime).count()<<" milliseconds," <<chrono::duration_cast<chrono::microseconds>(endTime-startTime).count()<<" microseconds," <<chrono::duration_cast<chrono::nanoseconds>(endTime-startTime).count()<<" nanoseconds."<<endl; } void showTime6() { char *dtValue=(char*)malloc(20); for(int i=0;i<10;i++) { retrieveTime5(dtValue); printf("Index=%d,value=%sn",i,dtValue); sleep(1); } free(dtValue); } void retrieveTime5(char *dtValue) { time_t rawTime = time(NULL); struct tm tmInfo = *localtime(&rawTime); strftime(dtValue, 20, "%Y%m%d%H%M%S", &tmInfo); }
Declare
void passFunc(void(*funcName)());
Implement
void passFunc(void(*funcName)()) { (*funcName)(); }
Invoke
int main() { passFunc(&showTime6); return 0; }
When the function with parameters,declare as below.
void callFunc6(void (*funcName)(char *));
Implementation
#include <uuid/uuid.h> void callFunc6(void (*funcName)(char *)) { char *uuidValue = (char *)malloc(40); (*funcName)(uuidValue); printf("UuidValue=%sn", uuidValue); free(uuidValue); } void retrieveUuid1(char *uuidValue) { uuid_t newUUID; uuid_generate(newUUID); uuid_unparse(newUUID, uuidValue); }
Invoke the function
int main() { call7(); return 0; } void call7() { callFunc6(&(retrieveUuid1)); }
Compile
g++ -g -std=c++2a -I. UtilityHelper.cpp h1.cpp -o h1 -luuid
The compact version as below.
void funcCall8(void(*funcName)()); void callFunc9(); void printNum(); int main() { callFunc9(); return 0; } void callFunc9() { funcCall8(&printNum); } void printNum() { for(int i=0;i<10;i++) { printf("Num=%dn",i); sleep(1); } } void funcCall8(void(*funcName)()) { (*funcName)(); }
原文链接: https://www.cnblogs.com/Fred1987/p/15660898.html
欢迎关注
微信关注下方公众号,第一时间获取干货硬货;公众号内回复【pdf】免费获取数百本计算机经典书籍;
也有高质量的技术群,里面有嵌入式、搜广推等BAT大佬
原创文章受到原创版权保护。转载请注明出处:https://www.ccppcoding.com/archives/401737
非原创文章文中已经注明原地址,如有侵权,联系删除
关注公众号【高性能架构探索】,第一时间获取最新文章
转载文章受原作者版权保护。转载请注明原作者出处!