Converting string into integer?

Question

// why can't I convert each element in a string into each integer in this situation?

string num = "7654382";
int length = num.Length;
while (x < length)
{
Console.WriteLine(Convert.ToInt32(num[x]));
x++;
}

//I am trying to find largest or second largest number or lowest number

Answer 1

Because num[x] returns a char type , for example num[0] returns '7' as a char not "7" as a string , and when converting it to a int it will return the Unicode of that character , in our example when converting '7' to int it will return 55 , to avoid this you can create a method that takes char as an argument and return the corresponding int , for example :
static int ConvertCharToInt(char digit)
{
switch (digital)
{
case '0':
return 0;
case '1':
return 1;
.
.
.
.

Answer 2

Thank you Rabee for making it clear!

Answer 3

Thank you Hasan