C/C++常用功能

时间函数：
 time_t T;time(&T);strftime(str, 255, "%Y-%m-%d %H:%M:%S", localtime(&T));
获取当前时间

程序耗时：
time_t begin;time($begin)difftime(time(NULL), begin);#include <time.h> clock_t start, end; double cpu_time_used; start = clock(); ... /* Do the work. */ end = clock(); cpu_time_used = ((double) (end - start)) / CLOCKS_PER_SEC;//return elapsed CPU time in microsecondsdouble cpu_time(){return (double) clock() / CLOCKS_PER_SEC * 1e6;}

 

 

参数检查：

int check_param(int argc, char **argv){ char stropt[] = "hes:i:o:l:";int c;if (argc == 1){print_usage(argv[0]);return -1;} while( (c = getopt(argc ,argv ,stropt)) != EOF) { switch(c) {case 's':sep=optarg;break;case 'i':infile=optarg;break;case 'o':outfile=optarg;break;case 'l':logfile=optarg;break;case 'h':print_usage(argv[0]);return -1;case 'e':g_daemon=1;break;default :cerr << "Error: unrecognized or incomplete command line." << endl;print_usage(argv[0]);return -1;} }return 0;}

 

计算数组大小：

int c[] = {1,2,3,4};for(int i = 0; i< sizeof(c)/sizeof(*c); i++)c[i]++ ;

C++I/O

cout << flush; //清空流//把基数变为oct(八进制)，dec(十进制)或hex(十六进制)：cout << hex << "0x" << i << endl;//跳过空格cin >> ws;