Ok, I see. I just tested a bit this, and it's working ok. I will need some time to digest all this info (and faked info too ;P). If new quiery appear I will shout for help.:-D Thx, can I send to u some info about the robot, and some methods I intend to use to solve some problems? By the way are u good in maths? (probability and statistics?) If u want to answer to this, send the answer on my e-mail, plz. _____________________________ THX

Who could explain to me how getline is working? I checked already a tutorial about it, but I didn't understand well. THX

yep is ok about binary. Yet there is still a problem. The objectA must be a const char*, that is not. U said to me :

class A
{
public:
double x;
double y;
double speed;
double z;
};

As u can see here if I want to write the x, y, z. I could do as:

main(int argc, char *argv[])
{
A objectA;

fstream File;
File.open ("test.txt", ios::binary);

File.seekp(0);

objectA.x=25.314;//xcoord
objectA.y=-478.215;//ycoord
objectA.z=34821.01;//zcoord

Up to here nothing wierd. But then when I want to write into file I will use:

File.write(&objectA.x, sizeof(objectA.x));

And the error will be: 'class ostream &__thiscall ostream::write(const char *,int)' : cannot convert parameter 1 from 'double *' to 'const char *' And even if I will write simply :

File.write(&objectA, sizeof(objectA));

There will still be the same error: 'class ostream &__thiscall ostream::write(const char *,int)' : cannot convert parameter 1 from 'class A *' to 'const char *' :confused: I might have get things wrong...:doh: THX

Is it possible to get the size of datas to be written to file and then use this (their size), to be able to retrieve the right data? THX

ok got y. thx again. Though u didn't say to me what u meant by the lenght of a line. Does space and zero count in this lenght? i'm talking about the seekg(). Is this seekg() givin' me the possibility to read only a certain length of the file? THX

Hi. Everything is nice about what u said to me for reading and writing to files. Except one or two things. :( Well first of all it cannot convert from objectA to char*. That's why I didn't use this method before, because I couldn't handle this stuff. Anyway why do u have to use binary files?

outfile.write ((char*)objectA, sizeof(objectA)); //this line writes the complete
objectA(field by field) into the file test.txt.
Remember, the file contents are now binary.
So u may see many strange character when you open test.txt in a notepad.

THX

Ok I like this idea. I will try to use it. Could i, in case i want more details contact u on ur private mail? THX

OK thx. Got the trick ! sorry for the deformation of skeeg :) I was in a rush to get the train.

First thx for friday. Then what do u mean by the same length? Is space or tab considered as getting in the value's lenth? Or just by adding zeros at the end? I looked in a tutorial for the skeeg stuff and didn't understand well how it works. Could u breif me about this, please? THX

i used here "<< " just to visualise things better, but if u have a better idea say it to me please :) THX

Thx a lot, I really thought i will get no answer to my silly queston. ;P Though is there a method that will allow me to read no matter what line of the text file, without being obliged to read all the file? I mean like positioning the "cursor" to a certain position and read from there? What I mean is if I have a bigger file as: -2363824.109 (x position) 4870666.240 (y position) 2.18 (speed) 4566888.0035 (z position) 58.6544 (something) 269.2 (something) And i if i want to retrieve for example the 3rd line. Is there a simple solution? THX

I have a file that contains the following datas: -2363824.109 (x position) 4870666.240 (y position) 2.18 (speed) I want to read from this file either just the x position, either the y position, either the speed. I did the following: int main(int argc, char *argv[]){ ifstream GPSFile; //mode lecture GPSFile.open("C:\\My Files\\GPSFile\\GPSFile.txt", ios::in);//ouvre le fichier //c'est le fichier où on écrit les datas du gps double CataCoordX, CataCoordY; double gpsx=0, gpsy=0; while (!GPSFile.eof()){//tant que le fichier reste ouvert if (GPSFile.rdstate() == ios::failbit){cout<<"ERROR, \n";} ///GPSFile.seekg(ios::beg); //go to the beginning of the file GPSFile >> gpsx;//on lit GPSFile >> gpsy;//on lit CataCoordX=gpsx;//la première val devient les coord sur x CataCoordY=gpsy;//la deuxième val devient les coord sur y }//endwhile cout << CataCoordX < This will print : 2.18 4.87067e+006 But me i want to print the first and the secon value. How to do this? THX

I thought ifstream is made for reading files only, and ofstream to be able to write into file. Did I miss something there? I want to write the values cellsV[i][j] into the BuiltMap file. THX

I want to insert the values i get from a matrix, in the order thay are in a text file. I mean by this the values to keep their place, on lines and columns. To read the values I did this: double LocalMap::SquareValue(int i, int j) { for (i=0; i0){ cellsV[i][j]=cellV[i][j]*cellV[i][j]; if (cellsV[i][j]>noise_border){ ofstream BuiltMap; //mode écriture BuiltMap.open ("C:\\My Files\\BuiltMap\\BuiltMap.txt", ios::in); //open file while (!BuiltMap.eof()){ //laisser i colonnes libres et j espaces libres BuiltMap<<"\n"<<" "<

I am quite a beginner myself, but I think u can use pointers to do this. Something like: char *ptrs=NULL; char s[20]="a, c, d, f, l, m"; ptrs=&s[3];//pointer points le address of s[3] printf(" %d\n", s[3]);//should print the address *ptrs=63; //value of pointer is 63 printf(" %d\n", s[3]);//should print 63 I think this is not correct, but might give you ideas. :doh: THX