help with c++ ifstreams

Question

so im reading numbers from a txt file that look like:
3
8 1 6
3 5 7
4 9 2

i only need to store 3 in the value of n, without using getline, 3 is what i read first to make the 3x3 matrix below

when i use my while loop:

while(read >> n){
cout << n << endl;
}

it displays all the numbers an i only need n = 3
how can i get it to only read 3?

Answer 1

Baric You will need to do more work,but,

you're welcome!

Answer 2

/*bad practice using auto but

try this

picked fileData instead of n

*/

for( auto fileData : read){
try{
if(atoi(fileData) == 3){
cout << fileData << endl;

}

}
catch(...){}

}

Answer 3

Try it see what happens.

Answer 4

If you want to just read 3, and you can be sure that 3 is on the first line, assuming inData is your ifstream object,

inData >> n;

Yep.

Answer 5

still a bit confused that's pretty advanced, havent gone over that in class but it helped :)

Answer 6

thank you

Answer 7

will this only work for 3 because I need to run it for 5x5 matrix an 7x7 an 9x9 all in the same txt file 3x3 is just the first one

Answer 8

i needed to set it to a function in the while

while(read >> n){
loadnumbers(array[][], size);
}

void loadnumbers(int n, int array[size][size]){
for (int row = 0; row < n; row++){
for(int col = 0; col < n; col++){
read >> array[row][col]
}
}
}