CODEWITHSUNDEEP
c
Krishna Choudhary
Krishna Choudhary

Reputation: 11

There is a problem with calling the function within the function

//Program to print the summation of a five-digit or less than 5 digit number entered using recursion.

#include <stdio.h>
#include <conio.h>

int summation(long int num) //summation function.
{
    int sum = 0, rem;
    if (num < 10)
        return num;
    else
    {
        for (int i = 0; i <= 4; i++)
        {
            rem = num % 10;
            sum = sum + rem;
            summation(num / 10);
        }
        return sum;
    } //End else.

} //End summation.

int main()
{
    long int data;
    int ans;
    int summation(long int num);
    clrscr();
    printf("Enter a number");
    scanf("%ld", &data); //Taking the input of data.
    ans = summation(data); //Calling the funcion.
    printf("%d", ans); //Printing the output.
    getch();
    return 0;
} //End main.

In this program, when I called the function by passing the argument as num/10 then it gave a wrong answer. Instead, if I wrote num =num/10 and called the function by passing num as an argument I got the right answer. Why is this happening? Are both statements the same thing?

Upvotes: 1

Views: 87

Answers (2)

tripleee
tripleee

Reputation: 189307

You are mixing recursion and loops. Use either, but not both. (Of course, the assignment says to use recursion, so do that.)

Loop solution (pseudocode):

int summation(number) {
    for (digit in number)
        sum += digit;
    return sum;
}

Recursion (pseudocode):

int summation(number) {
    if (number < 10) return number;
    else {
        dv = number%10;
        return dv + summation(number // 10);
    }
}

Notice how the latter calls itself, and also how that call returns the value from the new call to the caller, building a chain between them.

Upvotes: 1

user8234870
user8234870

Reputation: 

#include<stdio.h>
int summation(int);
int main(){
    int val,sum;
    scanf("%d",&val);
    sum=summation(val<0?-val:val);//We need the absolute value
    printf("%d",sum);
    return 0;
}
//Get the sum recurcively
int summation(int v){
    if(v==0)
    return 0;
    return (v%10)+summation(v/10);//v%10 is the reminder which is the last digit
}

Upvotes: 0

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