for (int i - 0; i < 10; ++i) {
char filePath[100] = "./";
char index[1] = { 0 };
sprintf(index, "%d", i);
strcat(filePath, index);
strcat(filePath, ".txt");
ofstream f(filePath);
f << data << endl;
}
for (int i - 0; i < 10; ++i) {
char filePath[100] = "./";
char index[1] = { 0 };
sprintf(index, "%d", i);
strcat(filePath, index);
strcat(filePath, ".txt");
ofstream f(filePath);
f << data << endl;
}