Please help a biginner

**KOFI** · 04-01-2010

I want to write a short code to sum the digits of a 5digit number. Someone please help me to developed the pseudo code and maybe the approach to write to code. Thanks.

**laserlight** · 04-01-2010

What ideas do you have?

**rob90** · 04-01-2010

You can do something like:

Code:

while(n > 0) 
sum += n%10;  // sum is 0 at the beginning
n /= 10;

using the mod operator you take the last digit of the number and decrement the number dividing it by 10

**MK27** · 04-01-2010

Do modulus ten on the number to get the last digit, then divide by ten (C rounds down), and repeat.

Looks like rob90 beat me.

**KOFI** · 04-01-2010

I was looking at an array approach...what do you think?

**KOFI** · 04-01-2010

Thanks rob90 but I was hoping for some rather simple approach to it..like an array approach. Help please..

**laserlight** · 04-01-2010

Originally Posted by KOFI

I was looking at an array approach...what do you think?

If you read in the number as a string, that certainly is a good idea, otherwise you might as well use what has been suggested.

**rob90** · 04-01-2010

Yes, you should take the number as a string and then read each element of the array and convert it to an integer to make the sum, but I think that using the modulus is even simpler

**MK27** · 04-01-2010

Originally Posted by KOFI

Thanks rob90 but I was hoping for some rather simple approach to it..like an array approach. Help please..

I'm gonna third the opinion that modulus/division is the simplest method, but if you want to use an array:

[edit] corrected from sscanf to sprintf

Code:

int x = 54321;
char array[6];  // we need room for the null terminator
ssprintf(array, "%d", x);

"array" is now a string version of x, where each character is a single digit. You will now need to consult the ASCII table to do arithmetic with it:

ASCII Table / Extended ASCII Codes

Which is not a bad idea, ASCII is very fundamental to even basic C programming. Feel free to ask questions.

**laserlight** · 04-01-2010

Originally Posted by MK27

You will now need to consult the ASCII table to do arithmetic with it:

Luckily, you don't: you can just subtract '0'.

**MK27** · 04-01-2010

Originally Posted by laserlight

Luckily, you don't: you can just subtract '0'.

Why does that work, laserlight?

**laserlight** · 04-01-2010

Originally Posted by MK27

Why does that work, laserlight?

Because it is guaranteed that for any standard conforming implementation, the sequence of digits in the character set from '0' to '9' will be contiguous.

**MK27** · 04-01-2010

I still think KOFI will be missing out on the excitement, unless...

ASCII Table / Extended ASCII Codes

**nonoob** · 04-01-2010

I think it's sprintf()

**MK27** · 04-01-2010

Originally Posted by nonoob

I think it's sprintf()

Yeah, eerie, I was just doing more or less this exact thing and then suddenly remembered something...anyway fixed.

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