How to display variables in a text document?

Question

C++ / C#

In general, according to the assignment, the values ​​​​of the matrix after summation should be output to a txt file in a certain order.
As I understand it, this is done through FILE and fopen, but can someone specifically parse everything in detail? Thanks in advance for your replies.
PS on the example of just some two variables

Answer 1

int a = 0; //переменная
int b = 0; //переменная

FILE* file = fopen("file.txt", "w"); //открытие файла с разрешением на запись
fprintf(file, "%d %d ", a, b);//запись в файл формат-строкой с пробелами

fclose(file); // закрытие файла