Appending text to a file

Question

I am trying to append data into a file, and I am having trouble in checking if the input data is already there in the file. If the data is already there in the file, then it won't add that data again. Can anyone tell me what shall I do in this case? I have attached a copy of my code for your reference. Thanks!

void addentry(char* name, char* entry){

ifstream in_file(name);
ofstream out_file(name, ios::app);


out_file << entry << endl;

if(!in_file) {
   cout << "This is the first entry of this person" << endl;
} 


int_file.close();
out_file.close();
}

How does a human tell if a word is written on a page in a book? — JohnFilleau, Apr 11 '20 at 16:26
In a nutshell: read the file into memory. Check if the data in question is already there. If it is; do nothing, if it isn't; append it to the file. — Jesper Juhl, Apr 11 '20 at 16:27
as @JesperJuhl said read the file, but not all of it when unnecessary, read for instance line per line until you find the word or you reach EOF, and if EOF add it — bruno, Apr 11 '20 at 16:30
https://stackoverflow.com/questions/2393345/how-to-append-text-to-a-text-file-in-c — adrien bedel, Apr 11 '20 at 16:48
https://stackoverflow.com/questions/2393345/how-to-append-text-to-a-text-file-in-c — adrien bedel, Apr 11 '20 at 16:51

score 2 · Accepted Answer · answered Apr 11 '20 at 16:36

2

read file data and count character till EOF (End of file). Check if count is not equal to zero. If it is so append else don't. You have not provided whole code otherwise I would have compiled and then send you code as well.

answered Apr 11 '20 at 16:36

Ankit Mishra

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3
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while(!input_file.eof()) { if (input_file.get(c)) { count++; } } – Pressing_Keys_24_7 Apr 11 '20 at 16:45
1

I have written this, but how shall I write my code as, when input file == entry, then count++? – Pressing_Keys_24_7 Apr 11 '20 at 16:46
Shall I use get function or getline function? – Pressing_Keys_24_7 Apr 11 '20 at 16:46
1

@user13218692 Handy reading: [Why is iostream::eof inside a loop condition (i.e. `while (!stream.eof())`) considered wrong?](https://stackoverflow.com/questions/5605125/why-is-iostreameof-inside-a-loop-condition-i-e-while-stream-eof-cons) – user4581301 Apr 11 '20 at 16:48
1

simply open file and start reading and have counter to count every character till end of file. use while loop. At the end check count if it is zero the append/write into file otherwise don't – Ankit Mishra Apr 11 '20 at 16:50
But, in that case how will i get to know if the character is equal to the entry? – Pressing_Keys_24_7 Apr 11 '20 at 16:54
Cause it will read and count every character inside the file right? Then how to check for the matching character? – Pressing_Keys_24_7 Apr 11 '20 at 16:55
1

You can have buffer of string and start checking till end. If it starts matching first letter then check till end of tha buffer and have a Chevy of status if it found or not using any flag. – Ankit Mishra Apr 11 '20 at 16:58

score 1 · Answer 2 · answered Apr 11 '20 at 16:44

To retrieve the data you must know how you inserted it . instead of writing in text file write in .ini file it will be really fast for your kind of operation . when you write in .ini file a single loop will do this stuff for you . to read about ini file i am attaching the links hope that will help you.

http://en.wikipedia.org/wiki/INI_file#Accessing_INI_files

http://sdl-cfg.sourceforge.net/

http://sourceforge.net/projects/libini/

http://www.codeproject.com/KB/files/config-file-parser.aspx

Appending text to a file

2 Answers2