You can convert char to int and viceversa easily because for the machine an int and a char are the same, 8 bits, the only difference comes when they have to be shown in screen, if the number is 65 and is saved as a char, then it will show ‘A’, if it’s saved as a int it will show 65.
With other types things change, because they are stored differently in memory. There’s standard function in C that allows you to convert from string to double easily, it’s atof. (You need to include stdlib.h)
#include <stdlib.h>
int main()
{
string word;
openfile >> word;
double lol = atof(word.c_str()); /*c_str is needed to convert string to const char*
previously (the function requires it)*/
return 0;
}