My skills are very basic. I'm trying to make save and load functions for a text game. This is my code:
#include <fstream>
#include <iostream>
#include <cstdlib>
#include <string>
#include <sstream>
#include "variables.h"
// CORE FUNCTIONS
void save_game()
{
std::ofstream file((savefile_path + "/" + player_name + ".txt").c_str());
if (file.is_open())
{
file << engine_switch << std::endl; //int
file << map_switch << std::endl; // int
file << sub_map_switch << std::endl; // int
file << player_name << std::endl; //string
file << player_class << std::endl; // string
//file << << endl;
file.close();
}
else
{
std::cout << "A PROBLEM OCCURED";
system("pause");
}
return;
}
void load_game()
{
system("cls");
std::cout << "ENTER THE SAVE FILE NAME (SAME AS YOUR CHARACTER NAME)\nOR PRESS ENTER TO GO BACK TO MAIN MENU: ";
fflush(stdin);
getline(std::cin, player_name);
std::string name=player_name;
std::ifstream file((savefile_path + "/" + player_name + ".txt").c_str());
if(file)
{
file >> engine_switch; // this is int
file >> map_switch; // this is int
file >> sub_map_switch; /this is int
file >> player_name; //string
file >> player_class; //string
//file >> ;
return;
}
else
{
if(player_name=="\0")
{
engine_switch=1;
return;
}
else
{
system("cls");
std::cout << "COULDN'T OPEN THE SAVE FILE" << std::endl;
system("pause");
load_game();
}
}
engine_switch=1;
return;
}
The problem happens when I enter a player_name compound of multiple words separated with a space. For example when I enter "name name" the player_name becomes name and the player_class becomes name and the actual player_class is not put into any variable.
I tried the rdbuf() function, but didn't work and I don't even understand it yet. I tried it with stream, string, c.str(), everything I found on the web and could comprehend, but it always comes out wrong.
When you extract a string from a stream, spaces are considered as separators.
It's even worse: in your code, the player_name is followed by player_class which is also a string. How should your program interpret this :
10 15 20 John William Doe hero B
How would your program guess that John William Doe is a composed name and hero B the category ?
The simplest solution is to write all your strings on a separate line in the file. When you load it you can then read it with getline():
file >> engine_switch; // this is int
file >> map_switch; // this is int
file >> sub_map_switch; /this is int
getline (file, player_name); //string
getline (file, player_class; //string
You need to use getline instead of the >> operator in your load-game function.
Instead of doing file >> player_name do getline(file, player_name)
This should be used in replacement of every occurrence of file >> someVar
EDIT: I didn't realize the others were integer values. For those you should still be using the >> operator.
Related
I want to load data from a Text file that has been created in the same program into a vector of strings. But no line of text is getting pushed into the vector here.
Here First I am reading data from some input file and then doing some operations (Removing extra spaces) on it then I save this file as "intermediate.txt". This intermediate.txt is being created and all the operations that I want to do happen successfully. Finally, I want to read this file into a vector<string> code but it doesn't work. I can't store anything in the vector<string> code. Its size is Zero.
#include <bits/stdc++.h>
using namespace std;
int main()
{
string inputFileName;
cout << "Enter the Input File Name: ";
cin >> inputFileName;
ifstream f1(inputFileName);
ofstream f0("intermediate.txt");
string text_line;
while (getline(f1, text_line))
{
string word;
istringstream text_stream(text_line);
while (text_stream >> word)
{
f0 << word << " ";
}
f0 << "\n";
}
f0.close()
ifstream file("intermediate.txt");
vector<string> code;
string line;
while (getline(file, line, '\n'))
{
code.push_back(line);
}
for (auto it : code)
{
cout << it << "\n";
}
}
Here's a mini-code review:
#include <bits/stdc++.h> // Don't do this; doesn't even compile for me
using namespace std; // Don't do this either
int main()
{
string inputFileName;
cout << "Enter the Input File Name: ";
cin >> inputFileName;
ifstream f1(inputFileName); // Bad name
ofstream f0("intermediate.txt"); // Bad name
// You never check that you successfully opened *any* files.
string text_line;
/*
* You don't describe why this is necessary, can a line not be read and
* written as-is? Is it already a line of space-separated variables?
*
* In any case, this is where you already have the words; so store them in
* the vector here as well.
*/
while (getline(f1, text_line))
{
string word;
istringstream text_stream(text_line);
while (text_stream >> word)
{
f0 << word << " ";
}
f0 << "\n";
}
f0.close() // Forgot your semi-colon
// Left f1 open, that's bad practice
ifstream file("intermediate.txt");
vector<string> code;
string line;
/*
* I would hope you felt that reading from a file, writing to a new file,
* closing both files, opening the new file, and reading from the new file
* into the vector was wasteful.
*/
while (getline(file, line, '\n'))
{
code.push_back(line);
}
for (auto it : code)
{
cout << it << "\n";
}
}
The most immediate issue with your original question was that you tried to open the same file in two different streams. The second time, the file failed to open, but because you never check if you actually opened the file, you assumed everything worked fine, but it didn't, which brought you here.
However, there is a better way.
#include <fstream>
#include <iostream>
#include <sstream>
#include <string>
#include <vector>
int main() {
std::string inputFileName;
std::cout << "Enter the Input File Name: ";
std::cin >> inputFileName;
// Always check that you successuflly opened the file.
std::ifstream fin(inputFileName);
if (!fin) {
std::cerr << "Error opening: " << inputFileName << ". Exiting...\n";
return 1;
}
std::ofstream fout("intermediate.txt");
if (!fout) {
std::cerr << "Error opening: intermediate.txt. Exiting...\n";
return 2;
}
std::vector<std::string> code;
std::string text_line;
while (std::getline(fin, text_line)) // You've read the line
{
std::string word;
std::istringstream text_stream(text_line);
while (text_stream >> word) {
fout << word << " ";
}
fout << "\n";
code.push_back(text_line); // Just store it while you have it
}
fin.close(); // Best practice is to close a file as soon as you're done
fout.close(); // with it. Don't hog resources.
for (const auto& it : code) // Avoid making copies
{
std::cout << it << "\n";
}
}
The while loop, where you read the lines that you want to store in the vector, now writes to your file and stores the lines into the vector. We also now check whether we successfully opened files, and we close the file streams as soon as we're done with the file so as to not keep it locked for no good reason.
A good next step for improving this program a bit more would be to avoid asking the user for a file name. Instead, take it as an argument to main(). That way, someone only has to type ./a.out input.txt on the command line and the program will do the job automatically.
i want to receive an input from user and search a file for that input. when i found a line that includes that specific word, i want to print it and get another input to change a part of that line based on second user input with third user input. (I'm writing a hospital management app and this is a part of project that patients and edit their document).
i completed 90 percent of the project but i don't know how to replace it. check out following code:
#include <iostream>
#include <stream>
#include <string.h>
#include <string>
using namespace std;
int main(){
string srch;
string line;
fstream Myfile;
string word, replacement, name;
int counter;
Myfile.open("Patientlist.txt", ios::in|ios::out);
cout << "\nEnter your Name: ";
cin.ignore();
getline(cin, srch);
if(Myfile.is_open())
{
while(getline(Myfile, line)){
if (line.find(srch) != string::npos){
cout << "\nYour details are: \n" << line << endl << "What do you want to change? *type it's word and then type the replacement!*" << endl;
cin >> word >> replacement;
}
// i want to change in here
}
}else
{
cout << "\nSearch Failed... Patient not found!" << endl;
}
Myfile.close();
}
for example my file contains this line ( David , ha , 2002 ) and user wants to change 2002 to 2003
You cannot replace the string directly in the file. You have to:
Write to a temporary file what you read & changed.
Rename the original one (or delete it if you are sure everything went fine).
Rename the temporary file to the original one.
Ideally, the rename part should be done in one step. For instance, you do not want to end up with no file because the original file was deleted but the temporary one was not renamed due to some error - see your OS documentation for this.
Here's an idea:
#include <iostream>
#include <fstream>
#include <string>
#include <cstdio>
using namespace std;
void replace(string& s, const string& old_str, const string& new_str)
{
for (size_t off = 0, found_idx = s.find(old_str, off); found_idx != string::npos; off += new_str.length(), found_idx = s.find(old_str, off))
s.replace(found_idx, old_str.length(), new_str);
}
int main()
{
const char* in_fn = "c:/temp/in.txt";
const char* bak_fn = "c:/temp/in.bak";
const char* tmp_fn = "c:/temp/tmp.txt";
const char* out_fn = "c:/temp/out.txt";
string old_str{ "2002" };
string new_str{ "2003" };
// read, rename, write
{
ifstream in{ in_fn };
if (!in)
return -1; // could not open
ofstream tmp{ tmp_fn };
if (!tmp)
return -2; // could not open
string line;
while (getline(in, line))
{
replace(line, old_str, new_str);
tmp << line << endl;
}
} // in & tmp are closed here
// this should be done in one step
{
remove(bak_fn);
rename(in_fn, bak_fn);
remove(out_fn);
rename(tmp_fn, in_fn);
remove(tmp_fn);
}
return 0;
}
One possible way:
Close the file after you read it into "line" variable, then:
std::replace(0, line.length(), "2002", "2003")
Then overwrite the old file.
Note that std::replace is different from string::replace!!
The header is supposed to be <fstream> rather than <stream>
you can't read and write to a file simultaneously so I have closed the file after reading before reopening the file for writing.
instead of updating text inside the file, your line can be updated and then written to file.
#include <iostream>
#include <fstream>
#include <string.h>
#include <string>
using namespace std;
int main(){
string srch;
string line, line2;
fstream Myfile;
string word, replacement, name;
int counter;
Myfile.open("Patientlist.txt", ios::in);
cout << "\nEnter your Name: ";
cin.ignore();
getline(cin, srch);
if(Myfile.is_open())
{
while(getline(Myfile, line)){
if (line.find(srch) != string::npos){
cout << "\nYour details are: \n" << line << endl << "What do you want to change? *type it's word and then type the replacement!*" << endl;
cin >> word >> replacement;
int index = line.find(word);
if (index != string::npos){
Myfile.close();
Myfile.open("Patientlist.txt", ios::out);
line.replace(index, word.length(), replacement);
Myfile.write(line.data(), line.size());
Myfile.close();
}
}
// i want to change in here
}
}else
{
cout << "\nSearch Failed... Patient not found!" << endl;
}
}
I know this is asked a lot, but I am spending hours to solve this problem. I am trying to edit txt file by replacing names. I copied my datas to the temp.txt file and when I enter the inputs, temp file does the job and changing the word. But the functions which are remove and rename are not working. My code is below:
string search_string;
string replace_string;
ofstream file;
file.open("temp.txt"); //opening file
cout<<"Enter the word you want to change: ";
cin>>search_string;
cout<<"Enter the new word: ";
cin>>replace_string;
string inbuf;
fstream input_file("musics.txt", ios::in);
ofstream output_file("temp.txt");
while (!input_file.eof())
{
getline(input_file, inbuf);
int spot = inbuf.find(search_string);
if(spot >= 0)
{
'this is the replacing part'
}
output_file << inbuf << endl;
remove("musics.txt");
file.close();
rename("temp.txt", "musics.txt");
}
You have 2 main problems.
You open the output file twice.
You must close all files before you do file operations
Especially the 2nd topic is causing the trouble.
Here a working solution:
#include <iostream>
#include <cstdio>
#include <fstream>
#include <regex>
// The filenames
const std::string musicFileName{ "music.txt" };
const std::string tempFileName{ "temp.txt" };
int main() {
// Open a new scope, so that the file streams
// will be closed automatically by the destructor
{
// Open the source file
std::ifstream sourceFile(musicFileName);
// Check, if it could be opened
if (sourceFile) {
// Source file is open, now open the temp file
std::ofstream tempFile(tempFileName);
// Check, if the tempfile could be opened
if (tempFile) {
// Both files are open, get the search and replace strings
std::string searchString;
std::string replaceString;
std::cout << "Enter the word you want to change: ";
std::cin >> searchString;
std::cout << "Enter the new word: ";
std::cin >> replaceString;
// Now read all lines from source file
std::string textLine{};
while (std::getline(sourceFile, textLine)) {
// Replace the text and write it to the destination file
tempFile << std::regex_replace(textLine, std::regex(searchString), replaceString) << "\n";
}
}
else {
std::cerr << "Could not open '" << tempFileName << "'\n";
}
} // <-- This will close the temp file
else {
std::cerr << "Could not open '" << musicFileName << "'\n";
}
} // <-- This will close the source file
// Remove and rename
std::remove(musicFileName.c_str());
std::rename(tempFileName.c_str(), musicFileName.c_str());
return 0;
}
#include <fstream>
#include <iostream>
#include <cstring>
using namespace std;
int main()
{
char filename[20] = "filename";
char userInput;
ofstream myFile;
cout << "Enter filename: ";
cin.getline(filename, sizeof(filename));
myFile.open(filename);
if(myFile.fail())
{
cout << "Error opening file: "
<< filename << "\n";
return 1;
}
cout << "Add text to the file: ";
cin.get(userInput);
while(cin.good() && userInput)
{
myFile.put(userInput);
cin.get(userInput);
}
myFile.close();
return 0;
}
Im having trouble terminating the input without force quiting it(It still writes to the file).
This is what I am supposed to do
Receives a line of input from the user, then outputs that
line to the given file. This will continue until the line input
by the user is “-1” which indicates, the end of input.
however I cannot work out the -1 part. Any help would be greatly appreciated everything else seems to work.
You're making things a bit more complicated than they need to be. Why C strings instead of std::string, for example? Using the right (standard-provided) classes generally leads to shorter, simpler and easier-to-understand code. Try something like this for starters:
int main()
{
std::string filename;
std::cout << "Enter filename" << std::endl;
std::cin >> filename;
std::ofstream file{filename};
std::string line;
while (std::cin >> line) {
if (line == "-1") {
break;
}
file << line;
}
}
First of all, the assignment asks to read a line from the user, character-wise input by get() shouldn't be the function to use. Use the member function getline() as you did to recieve the file name and use a comparison function to check against -1:
for (char line[20]; std::cin.getline(line, sizeof line) && std::cin.gcount(); )
{
if (strncmp(line, "-1", std::cin.gcount()) == 0)
break;
myFile.write(line, std::cin.gcount());
}
So I'm really stuck trying to figured this bug on the program that is preventing me from displaying the text of my program..
#include <iostream>
#include <iomanip>
#include <fstream>
#include <sstream>
#include <string>
#include <stdio.h>
using namespace std;
int main ()
{
ifstream infile;
ofstream offile;
char text[1024];
cout <<"Please enter the name of the file: \n";
cin >> text;
infile.open(text);
string scores; // this lines...
getline(infile, scores, '\0'); // is what I'm using...
cout << scores << endl; // to display the file...
string name1;
int name2;
string name3;
int name4;
infile >> name1;
infile >> name2;
infile >> name3;
infile >> name4;
cout << "these two individual with their age add are" << name2 + name4 <<endl;
// 23 + 27
//the result I get is a bunch of numbers...
return 0;
}
Is there any way cleaner or simple method i can used to display the file ?
All the method in the internet are difficult to understand or keep track due to
the file is open in loop..
I want a program that you type the name of the file and displays the file
the file will contain the following...
jack 23
smith 27
Also I need to obtain data from the file now I'm using the above code to obtain that information from the file...
loop is probably the best thing you can do.
so if you know the format you could simply do it like this
#include <iostream>
#include <fstream>
using namespace std;
int printParsedFile(string fileName) { // declaration of a function that reads from file passed as argument
fstream f; // file stream
f.open(fileName.c_str(), ios_base::in); // open file for reading
if (f.good()) { // check if the file can be read
string tmp; // temp variable we will use for getting chunked data
while(!f.eof()) { // read data until the end of file is reached
f >> tmp; // get first chunk of data
cout << tmp << "\t"; // and print it to the console
f >> tmp; // get another chunk
cout << tmp << endl; // and print it as well
} else {
return -1; // failed to open the file
}
return 0; // file opened and read successfully
}
you can call then this function for example in your main() function to read and display file passed as argument
int main(int argc, char** argv) {
string file;
cout << "enter name of the file to read from: "
cin >> file;
printParsedFile(file);
return 0;
}
I personally use stringstreams for reading one line at a time and parsing it:
For example:
#include <fstream>
#include <stringstream>
#include <string>
std::string filename;
// Get name of your file
std::cout << "Enter the name of your file ";
std::cin >> filename;
// Open it
std::ifstream infs( filename );
std::string line;
getline( infs, line );
while( infs.good() ) {
std::istringstream lineStream( line );
std::string name;
int age;
lineStream >> name >> age;
std::cout << "Name = " << name << " age = " << age << std::endl;
getline( infs, line );
}