c++ 筆記

fileIO

#include <stdio.h>FILE * pFile;pFile = fopen ("myfile.txt","w");fprintf (pFile, "Hi, %d+%d=%d\n",1,1,2);fclose (pFile);

#include<fstream>ofstream fout;fout.open("/path/to/file.txt");fout<<i<<endl;fout.close();

#define countof(ARRAY) (sizeof (ARRAY) / sizeof *(ARRAY))string fname="test.bin";float data[7]={5.1,3,2,9383,5.1,12,5.1};float data2[7];FILE *file2 = fopen(fname.data(), "wb");assert(file2);size_t n2 = fwrite(data, sizeof(float), countof(data), file2);assert(n2 == countof(data));fclose (file2);FILE *file = fopen(fname.data(), "rb");assert(file);size_t n = fread(data2, sizeof(float), countof(data), file);assert(n == countof(data));fclose (file);

Timer

struct Timer{    clock_t begin;    void time_start(){        begin = clock();        cout<<begin<<endl;    }    void time_end(){        cout<<begin<<endl;        clock_t end = clock();        double elapsed_secs = double(end - begin) / CLOCKS_PER_SEC;        cout<<end<<endl;        cout<<"Elapse Time: "<<elapsed_secs<<endl;    }};Timer tim;tim.time_start();//some code is running heretim.time_end();

OpenCV multiple channel

int sz[] = {2, 2, 60};Mat bigCube(3, sz, CV_8U, Scalar::all(255));cout<<bigCube.at<Vec<char,60>>(0,0)[0]<<endl;cout<<bigCube.at<char>(0,0)<<endl;

#define cn 60int sz[] = {2, 2, cn};Mat bigCube(3, sz, CV_8U, Scalar::all(255));cout<<bigCube.at<Vec<char,cn>>(0,0)[0]<<endl;

typedef Vec<uchar, 20> Vec20b;cv::Mat_<Vec20b> myMat(2,2);myMat.at<Vec20b>(1,1)(0)='a';cout<<myMat.at<Vec20b>(1,1)(0)<<endl;