1.2 Variables and Arithmetic Expressions

/*Print Fahrenheit-Celsius table: for fahr =0, 20, ... ,300*/
void ConvertFahrenheittoCelsius()
{
    int Fahr, Celsius;
    int lower, higher, step;
    
    lower = 0;
    higher = 300;
    step = 20;

    while (lower < higher)
    {
        Fahr = lower;
        Celsius = 5 * (Fahr - 32) / 9;
        printf("\t%d\t%d\n", Fahr, Celsius);
        lower = lower + step;
    }

namespace ConsoleApplication4
{
    class Program
    {
        static void Main(string[] args)
        {
            float Fahr, Celsius;
            int lower, higher, step;

            lower = 0;
            higher = 300;
            step = 20;

            Fahr = lower;
            while (Fahr < higher)
            {
                Celsius = (float)((5.0 / 9.0)*(Fahr - 32.0)); 
                Console.WriteLine("{0}, \t {1}", Fahr, Celsius);
                Fahr = Fahr + step;
            }

            Console.ReadLine();
        }
    }
}　

#include "stdafx.h"


int _tmain(int argc, _TCHAR* argv[])
{
    float Fahr, Celsius;
    int lower, higher, step;

    lower = 0;
    higher = 300;
    step = 20;
　　
    Fahr = lower;   /* The int is converted to float before the operation is done.*/
    while (Fahr <= higher)
    {
        Celsius = (5.0 / 9.0) * (Fahr - 32);
        printf("%3.0f %6.1f \n", Fahr, Celsius);
        Fahr = Fahr + step;
    
    }
    return 0;
}

 

The reason for multiplying by 5 and then dividing by 9 instead of just multiplying by 5/9 is that in C，as in many other languages,integer division truncates: any fractional part is discarded.

Printf is a general-purpose output formatting function, and it is just a useful function from the standard library of functions that are normally accessible to C programs.

　　

In C Sharp，double cannot implicitly be converted to float.

The printf conversion specification %3.0f says that a floating-point number is to be printed at least three
characters wide, with no decimal point and no fraction digits.