Programming Forums - View Single Post - Jumping to a specific line number in a text file

Adeil · Oct 29th, 2007, 7:54 PM

Hello, a friend has asked me to make a program for him, and in this program i need to read lines and interpret them from a script-type of file (by script-type, it will have text in it with commands that the program will execute, script as in typed script...kind of like what the web browser does with JavaScript.)

What i would like to know is if there is an easy way to just jump to a certain line in a text file, like line 687, for example, without having to start from the beginning and read each line to get to line 687?

If there isnt, i was planning on using something like this, but if you know a more efficient way that would be great.

 c++ Syntax (Toggle Plain Text) 
    char buffer[256];
    ifstream fi;
    fi.open(INPUT_FILE);
    for(int i=1; i<lineNumber; i++)
    {
        if(fi.eof())
        {
            // ran out of lines before lineNumber, handle the error with output maybe
            fi.close();
            break;
        }
        fi.getline(buffer,sizeof(buffer));
    }
    if(fi.is_open())
    {
        // the next fi.getline will have all the contents of that line
        fi.close();
    }
    char buffer[256];
    ifstream fi;
    fi.open(INPUT_FILE);
    for(int i=1; i<lineNumber; i++)
    {
        if(fi.eof())
        {
            // ran out of lines before lineNumber, handle the error with output maybe
            fi.close();
            break;
        }
        fi.getline(buffer,sizeof(buffer));
    }
    if(fi.is_open())
    {
        // the next fi.getline will have all the contents of that line
        fi.close();
    }

On a slightly different track, but on the same subject, would it be effective to load the entire text file into a multi-dimensional array, so for line 687 i could just call lines[686] (because lines[0] would be the line number 1)?

Oct 29th, 2007, 7:54 PM	#1
Adeil Newbie Join Date: Mar 2005 Location: St. Louis, USA Posts: 3 Rep Power: 0	Jumping to a specific line number in a text file Hello, a friend has asked me to make a program for him, and in this program i need to read lines and interpret them from a script-type of file (by script-type, it will have text in it with commands that the program will execute, script as in typed script...kind of like what the web browser does with JavaScript.) What i would like to know is if there is an easy way to just jump to a certain line in a text file, like line 687, for example, without having to start from the beginning and read each line to get to line 687? If there isnt, i was planning on using something like this, but if you know a more efficient way that would be great. c++ Syntax (Toggle Plain Text) char buffer[256]; ifstream fi; fi.open(INPUT_FILE); for(int i=1; i<lineNumber; i++) { if(fi.eof()) { // ran out of lines before lineNumber, handle the error with output maybe fi.close(); break; } fi.getline(buffer,sizeof(buffer)); } if(fi.is_open()) { // the next fi.getline will have all the contents of that line fi.close(); } char buffer[256]; ifstream fi; fi.open(INPUT_FILE); for(int i=1; i<lineNumber; i++) { if(fi.eof()) { // ran out of lines before lineNumber, handle the error with output maybe fi.close(); break; } fi.getline(buffer,sizeof(buffer)); } if(fi.is_open()) { // the next fi.getline will have all the contents of that line fi.close(); } On a slightly different track, but on the same subject, would it be effective to load the entire text file into a multi-dimensional array, so for line 687 i could just call lines[686] (because lines[0] would be the line number 1)?