how do you round numbers?

[iky]

for my assignment i have to round three different numbers in a function. the function only receives one integer, a number from 0-100. i have to round it to the nearest 10. for example, if i send the function 22, it will return 20; if i send in 78, it will return 80. im not sure how to do this. i tired a random number but it didnt work. this is what i put in the function:

int roundscore (int score) {
    if (score >= 15 && score <= 25)
        score = 20;
    else
        score=10;
    return score;
}

[helios]

Hint: play around with the % operator.

[Sandeep Tuniki]

Try this :

int roundscore(int score)
{
    int r;
    r = score%10;
    
    if( r>=5)
      score = score + (10-r);
    else
      score = score - r;
    
    return r;
}

Here r is the remainder obtained when divided by 10.
When r>=5, score has to be rounded to upper bound.
If it is less than 5 it has to be rounded to lower bound.

[JLBorges]

This is one way:

inline int round( int number )
{
    const int delta = number < 0 ? -5 : 5 ;
    return ( number + delta ) / 10 * 10 ;
}

[iky]

thank you everyone.

@sandeep. it worked fine when i returned score and not r.