Неявное преобразование переменных

#include <iostream>
 
using namespace std;
 
int main()
{
    int userCh;
    float tempCel, tempFahr;
    cout << "If you want convert temperature in Celsius to temperature in Fahrenheit push 1,\n";
    cout << "if you want convert temperature in Fahrenheit to temperature in Celsius push 2: ";
    cin >> userCh;
    switch(userCh)
    {
        case 1:
            cout << "Insert temperature in Celsius: ";
            cin >> tempCel;
            tempFahr = 9.0 /5.0 *tempCel +32.0;
            cout << "Temperature in Fahrenheit is: " << tempFahr << endl;
            break;
       case 2:
            cout << "Insert temperature in Fahrenheit: ";
            cin >> tempFahr;
            tempCel = (tempFahr -32.0) *5.0 /9.0;
            cout << "Temperature in Celsius is: " << tempCel << endl;
        break;
        default:
        {
            cout << "You inserted wrong symbol!" << endl;
        }
    }
    return 0;
}

tempFahr = 1 *tempCel +32;

tempFahr = tempCel +32;

tempFahr = tempCel +32

tempFahr == tempCel

case 1:
            cout << "Insert temperature in Celsius: ";
            cin >> tempCel;
            tempFahr = 9.0 /5.0 *tempCel +32.0;
            cout << "Temperature in Fahrenheit is: " << tempFahr << endl;
            break;

9/5

(int)(9/5)