How do I copy the string in a txt file?

Question

Here is an example of text file I am dealing with:

http://example.com/object1 50 0
http://example.com/object2 25 1
http://example.another.com/repo/objects/1 250 0
ftp://ftpserver.abc.edu:8080 13 5
...

I want to pass the url, size(the first number), and the priority(the second number) into array. Here is my code:

ifstream infile;
infile.open("ece150-proj2-input.txt");

//Get the number of lines in the text file
int lines = 0;
while (!infile.eof()) {
    string line;
    getline(infile, line);
    lines++;
}

//Get the components in the input file
char url[lines][50];
float size[lines];
float delay[lines];
for (int i = 0; i < lines; i++) {
    infile >> url[i] >> size[i] >> delay[i];
}

//Testing if I get the url address correctly
cout << url[0] << endl;
cout << url[1] << endl;

However the result are some strange character:

pĞQ?
?Q?

Why is this happen? Can anyone solve this problem. Thank you ;-)

Answer 1

The issue here is that when you read through the file once the stream is now at the end of the file. You need to either call infile.seekg(0, infile.beg); to rewind to the beginning of the stream. You could also close and reopen infile.

Secondly you are declaring char url[lines][50]; You can not do this. The length of arrays in c++ must be compile time constants. I'm actually surprised your code compiled and gave you any output at all.

I would recommend that you use std::vector which is like an array but you can add elements to the end. That way you do not need to know the number of lines before hand.