Thread: Total newbie to programming C! Need help...

Hi,

For reference, I am using ANSI C.

I'm a complete noob when it comes to C and pretty much all programming, so p
lease bare with me! I'm sure this will be extremely easy to you guys, but I'
m pretty clueless.

I have 2 questions.

I am currently writing a program to use the Newton Raphson method to find a
root to an equation. The equation is a non variable. All the user has to do
is enter the starting value.

Basically, for those unfamiliar with this mathematical method, you enter a v
alue for x, and the equation works out a new value for x. You keep doing thi
s until your value of x becomes pretty much the same.

I want my program to keep doing the equation until the difference between th
e two x values is less than 0.001. I'm pretty sure I have to use a do while
loop, but I have no idea how to go about it. Any help would be extremely app
reciated.



Secondly, this is probably really simple, but I just don't know how to begin
. I am writing a program where the user enters a date in the following fashi
on:

01 05

ie - the above date would be the first of May, or:

06 02

Would be the 6th of february. Then, the user enters a second date in the sam
e manner. It is then calculated how many days are between the two dates the
user enters, and it is displayed.

Feb can be taken to have 28 days, so the leap year isn't an issue. But I rea
lly don't know what to do with this. Help would, again, be massively appreci
ated.

Thanks for taking your time to read this, and any help you may offer!

This calculates the number of days between two dates. I haven't thoroughly tested this function. So, it's your responsibility to test it.

Have fun
Bob

Code:

#include <stdio.h>
unsigned long JulianDaysCalc(int iMonth, int iDay, int iYear)
{
    //Calculation of serial Julian date
    int iTemp;
    int iYearCalc;
    int iMonthCalc;
    unsigned long ulSerialJulianDate;
    iTemp = (14 - iMonth)/12;
    iYearCalc = iYear + 4800 - iTemp;
    iMonthCalc =  iMonth+ (12*iTemp) - 3;
    ulSerialJulianDate = iDay + (((153*iMonthCalc) +2)/5) + (365*iYearCalc)
        + (iYearCalc/4) - (iYearCalc/100)+ (iYearCalc/400) - 32045;
    return ulSerialJulianDate;
}


int main(void)
{
    unsigned long ulJdate1, ulJdate2;
    ulJdate1 = JulianDaysCalc(11, 22, 2005);
    ulJdate2 = JulianDaysCalc(11, 20, 2005);
    printf(" Date diff %ld\n", (ulJdate1 - ulJdate2));
    return 0;
}