I just want to read a txt file and receive a string file like that
Blob rgbBlob;
string strIccRGBFile = "./icc/RGB.icc";
string strIccRGBContent = LoadFile(strIccRGBFile);
rgbBlob.update(strIccRGBContent.c_str(), strIccRGBContent.length());
image.profile("ICM", rgbBlob);
How I implement LoadFile function
#include <fstream>
#include <string>
int main()
{
std::string buff;
std::fstream fs("filename",std::ios::in | std::ios::ate)
if(fs.is_open())
{
fstream::pos_type size = fs.tellg();
fs.seekg(0);
buff.resize(size);
fs.read(&buff[0],size);
}
std::cout << buff << endl;
}
this is an example of how to read a file in it's entirety to a string buffer. It should give you a good idea on how to proceed.
Related
This question already has answers here:
Read whole ASCII file into C++ std::string [duplicate]
(9 answers)
How do I read an entire file into a std::string in C++?
(23 answers)
Closed 8 months ago.
I would like to read and display the content of a file entered by user at run-time
My code :
#include<iostream>
#include<fstream>
#include<stdio.h>
using namespace std;
int main()
{
char fileName[30], ch;
fstream fp;
cout<<"Enter the Name of File: ";
gets(fileName);
fp.open(fileName, fstream::in);
if(!fp)
{
cout<<"\nError Occurred!";
return 0;
}
cout<<"\nContent of "<<fileName<<":-\n";
while(fp>>noskipws>>ch)
cout<<ch;
fp.close();
cout<<endl;
return 0;
}
output :
C:\Users\prade\Desktop>g++ -o file file.cpp&file.exe
Enter the Name of File: tt.txt
Content of tt.txt:-
Hello , I am c++.
I am from us.
I am a programmer.
C:\Users\prade\Desktop>
I want to set the content of file to value of string str. I want to print the whole file's content by using cout<<str;
How can I do that ?
If you need to read the whole content of a text file into a std::string, you can use the code below.
The function ReadTextFile uses std::ifstream ::rdbuf to extract the content of the file into a std::stringstream. Then it uses std::stringstream::str to convert into a std::string.
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
bool ReadTextFile(std::string const & fileName, std::string & text)
{
std::stringstream strStream;
std::ifstream fileStream(fileName);
if (!fileStream.is_open())
{
return false;
}
strStream << fileStream.rdbuf();
fileStream.close();
text = strStream.str();
return true;
}
int main()
{
std::string text;
if (!ReadTextFile("t.txt", text))
{
std::cout << "failed" << std::endl;
return 1;
}
std::cout << text << std::endl;
return 0;
}
A side note: better to avoid using namespace std - see here Why is "using namespace std;" considered bad practice?.
Instead of extracting a single character from stream, you get extract a complete line using getline(). Your while loop should be something like this:
std::string line, contents;
while(getline(fp, line)) {
contents += line;
contents += "\n";
}
std::cout << contents;
Note that the above method is not efficient.
I am trying to open a csv file in C++ using ifstream with a directory in the file path name. The file does reside in the specified directory location, but I observe an for the variable inFile when executing the code. My research up to this point says the code is correct, but something obviously is wrong. Any suggestions?
Thanks,
KG
#include <string>
#include <fstream>
#include <iostream>
virtual void run()
{
string file_dir = "/home/datafiles/";
string csvFile = file_dir + "/myFile.csv";
ifstream inFile;
inFile.open("csvFile", ios::in);
// file check to see if file is open
if(!inFile.is_open()) {
cout << "error while opening the file" << endl;
}
}
I found the answer to my csv file opening problem, a colleague assisted.
#David - You suggested removing the double quotes in the "inFile.open" line of code. In addition to removing the double quotes, I also needed to add c_str(), which "returns a pointer to a null-terminated character array with data equivalent to those stored in the string," .data() also performs the same function (cppreference.com).
#user4581301 - I am also aware that ios::in is implied with a ifstream, only included it here as a reference; thanks.
The modified code is listed below:
#include <string>
#include <fstream>
#include <iostream>
virtual void run()
{
string file_dir = "/home/datafiles/";
string csvFile = file_dir + "/myFile.csv";
ifstream inFile;
inFile.open(csvFile.c_str(), ios::in);
// file check to see if file is open
if(!inFile.is_open()) {
cout << "error while opening the file" << endl;
}
}
Really appreciate all the help.
Enjoy,
KG
Is this what you're trying to do?
#include <iostream> // std::{ cout, endl }
#include <string> // std::{ string, getline }
#include <fstream> // std::ifstream
auto main() -> int {
// Just to demonstrate.
// You want to use your real path instead of example.cpp
auto file = std::ifstream("example.cpp");
auto line = std::string();
while ( std::getline(file, line) )
std::cout << line << '\n';
std::endl(std::cout);
}
Live example
In this function what I have to do is pass the strings from txt file in char and do some operations. My only problem is on pass file from txt to char. how i should fix it?
char* foo(string& input){
stringstream ss;
ss<<input;
char *elements=new char[32];
elements[32]='\0';
ss>>elements; //next part code not written because useless
This is how you can store data in a char array from a file:
Source File
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
ifstream inFile;
inFile.open("Input File.txt");
char Array[50] = { ' ' };
inFile.get(Array, 50);
cout << "Output : " << Array << endl;
inFile.close();
}
Text File
Enter Text Here
If you want i can make a dynamic array for you which will have the exact size as the string (Data you input) from file or use vectors because they can easily be expanded and shortened in late binding(means: during program execution).
I'm in a tutorial which introduces files (how to read from file and write to file)
First of all, this is not a homework, this is just general help I'm seeking.
I know how to read one word at a time, but I don't know how to read one line at a time, or how to read the whole text file.
What if my file contains 1000 words? It is not practical to read entire file word after word.
My text file named "Read" contains the following:
I love to play games
I love reading
I have 2 books
This is what I have accomplished so far:
#include <iostream>
#include <fstream>
using namespace std;
int main (){
ifstream inFile;
inFile.open("Read.txt");
inFile >>
Is there any possible way to read the whole file at once, instead of reading each line or each word separately?
You can use std::getline :
#include <fstream>
#include <string>
int main()
{
std::ifstream file("Read.txt");
std::string str;
while (std::getline(file, str))
{
// Process str
}
}
Also note that it's better you just construct the file stream with the file names in it's constructor rather than explicitly opening (same goes for closing, just let the destructor do the work).
Further documentation about std::string::getline() can be read at CPP Reference.
Probably the easiest way to read a whole text file is just to concatenate those retrieved lines.
std::ifstream file("Read.txt");
std::string str;
std::string file_contents;
while (std::getline(file, str))
{
file_contents += str;
file_contents.push_back('\n');
}
I know this is a really really old thread but I'd like to also point out another way which is actually really simple... This is some sample code:
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main() {
ifstream file("filename.txt");
string content;
while(file >> content) {
cout << content << ' ';
}
return 0;
}
I think you could use istream .read() function. You can just loop with reasonable chunk size and read directly to memory buffer, then append it to some sort of arbitrary memory container (such as std::vector). I could write an example, but I doubt you want a complete solution; please let me know if you shall need any additional information.
Well, to do this one can also use the freopen function provided in C++ - http://www.cplusplus.com/reference/cstdio/freopen/ and read the file line by line as follows -:
#include<cstdio>
#include<iostream>
using namespace std;
int main(){
freopen("path to file", "rb", stdin);
string line;
while(getline(cin, line))
cout << line << endl;
return 0;
}
The above solutions are great, but there is a better solution to "read a file at once":
fstream f(filename);
stringstream iss;
iss << f.rdbuf();
string entireFile = iss.str();
you can also use this to read all the lines in the file one by one then print i
#include <iostream>
#include <fstream>
using namespace std;
bool check_file_is_empty ( ifstream& file){
return file.peek() == EOF ;
}
int main (){
string text[256];
int lineno ;
ifstream file("text.txt");
int num = 0;
while (!check_file_is_empty(file))
{
getline(file , text[num]);
num++;
}
for (int i = 0; i < num ; i++)
{
cout << "\nthis is the text in " << "line " << i+1 << " :: " << text[i] << endl ;
}
system("pause");
return 0;
}
hope this could help you :)
hello bro this is a way to read the string in the exact line using this code
hope this could help you !
#include <iostream>
#include <fstream>
using namespace std;
int main (){
string text[1];
int lineno ;
ifstream file("text.txt");
cout << "tell me which line of the file you want : " ;
cin >> lineno ;
for (int i = 0; i < lineno ; i++)
{
getline(file , text[0]);
}
cout << "\nthis is the text in which line you want befor :: " << text[0] << endl ;
system("pause");
return 0;
}
Good luck !
Another method that has not been mentioned yet is std::vector.
std::vector<std::string> line;
while(file >> mystr)
{
line.push_back(mystr);
}
Then you can simply iterate over the vector and modify/extract what you need/
The below snippet will help you to read files which consists of unicode characters
CString plainText="";
errno_t errCode = _tfopen_s(&fStream, FileLoc, _T("r, ccs=UNICODE"));
if (0 == errCode)
{
CStdioFile File(fStream);
CString Line;
while (File.ReadString(Line))
{
plainText += Line;
}
}
fflush(fStream);
fclose(fStream);
you should always close the file pointer after you read, otherwise it will leads to error
As somebody who is new to C++ and coming from a python background, I am trying to translate the code below to C++
f = open('transit_test.py')
s = f.read()
What is the shortest C++ idiom to do something like this?
The C++ STL way to do this is this:
#include <string>
#include <iterator>
#include <fstream>
using namespace std;
wifstream f(L"transit_test.py");
wstring s(istreambuf_iterator<wchar_t>(f), (istreambuf_iterator<wchar_t>()) );
I'm pretty sure I've posted this before, but it's sufficiently short it's probably not worth finding the previous answer:
std::ifstream in("transit_test.py");
std::stringstream buffer;
buffer << in.rdbuf();
Now buffer.str() is an std::string holding the contents of transit_test.py.
You can do file read in C++ as like,
#include <iostream>
#include <fstream>
#include <string>
int main ()
{
string line;
ifstream in("transit_test.py"); //open file handler
if(in.is_open()) //check if file open
{
while (!in.eof() ) //until the end of file
{
getline(in,line); //read each line
// do something with the line
}
in.close(); //close file handler
}
else
{
cout << "Can not open file" << endl;
}
return 0;
}