https://robark.gitlab.io/streams/index.htmlStreams File I/O, stringstreamsHugoen-usTue, 01 Jun 2021 22:47:18 +0000https://robark.gitlab.io/streams/fileio/index.htmlThu, 27 May 2021 22:52:27 +0000https://robark.gitlab.io/streams/fileio/index.htmlFile I/O Various ways to read from a file #include <iostream> #include <fstream> using namespace std; // dumps file to screen int main() { string line,word; ifstream f("mydata.txt"); //ifstream f; //f.open("mydata.txt", ios::in); cout<<"----------reading by line -----------------------"<<endl; //ex #1 while ( getline(f,line) ) //line delimeted { cout<<line<<endl; } //f.close(); //f.open("mydata.txt", ios::in); f.clear(); // clear eof state flag from true to false //f.seekg(0); // set seek get file pointer to beginning of file //f.seekg(0,ios::beg); f.seekg(0,f.beg); //resets file pointer back to the top cout<<"----------reading by words-----------------------"<<endl; //ex #2 while ( f >> word ) //space delimited { cout<<word<<endl; } f.clear(); f.seekg(0,ios::beg); //set seek get file pointer with offset, so 0 offset from beginning of file cout<<"-----------reading by line but using eof() or good()----------------------"<<endl; //ex #3 //while ( !f.eof() ) while ( f.good() ) { getline(f,line); //use with !f.eof() cout<<line<<endl; } cout<<"-----------reading by character-----------------------"<<endl; f.clear(); f.seekg(0,ios::beg); //set seek get file pointer with offset, so 0 offset from beginning of file //ex #4 char c; while ( f.get(c) ) { cout<<c; } f.close(); return 0; } Reading and Writing from a filehttps://robark.gitlab.io/streams/structs/index.htmlFri, 28 May 2021 23:00:36 +0000https://robark.gitlab.io/streams/structs/index.htmlStructs and overloading operators #include <iostream> using namespace std; struct stud{ string name; int age; }; int main(){ stud a,b; a.name="bob"; a.age=19; b=a; cout<<b.name << b.age; return 0; } Overriding ctor #include <iostream> using namespace std; struct Stud{ Stud(); //default ctor Stud(string , int ); //variables optional string name; int age; }; Stud::Stud(){} Stud::Stud(string n, int a){ name=n; age=a; } int main(){ Stud a; Stud b("mary",22); a.name="bob"; a.age=19; cout<<b.name << b.age; b=a; cout<<b.name << b.age; return 0; } Initialization listshttps://robark.gitlab.io/streams/args/index.htmlTue, 01 Jun 2021 22:47:18 +0000https://robark.gitlab.io/streams/args/index.htmlCommand line arguments and Try Catch Argc Argv #include <iostream> #include <vector> #include <fstream> using namespace std; bool vec2file(const vector<string> &s, string filename) { //write vector to a file ofstream fout(filename); for (unsigned int x=0; x<s.size(); x++) { fout << s[x] << endl; } fout.close(); return true; } vector<string> file2vec(string filename) { //read a file and return vector vector <string> strvect; string line; ifstream fin(filename); while (getline(fin,line)) { strvect.push_back(line); } fin.close(); return strvect; } int main(int argc, char* argv[]) { string fname = argv[1]; vector <string> food = file2vec(fname); string grocery(""); while (1) { cout<<"enter grocery to buy or quit to end: "; getline(cin, grocery); if (grocery == "quit") break; food.push_back(grocery); } cout<<"\nprinting list of groceries to buy"<<endl; for (unsigned int y=0; y<food.size(); y++) { cout << food[y] << endl; } vec2file(food, fname); return 0; } Try/Catch