simple Recursion program - strange output

i want to write program which prints all natural numbers from 1 to n.
where n is user input. but i want to write using recursion and not by for loop.
ex. if user enters 5 then output should be 1 2 3 4 5
i tried following code but its not working.

Code:

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#include <stdio.h>#include <stdlib.h>


int main()
{
    int n;
    printf("enter no.");
    scanf("%d", &n);
    rec(n);
    return 0;
}


int rec(int n) {
    if(n==1) {
        printf("1\n");
    }
    else {
            n--;
            printf("%d\n",rec(n));
    }
}

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the output is 1 0 2 2 2....upto n.

please help me and can anyone tell me whats the mistake in this code
thanks

You might find it easier to work with:

Code:

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int rec(int i, int n) {

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please can you explain me? how to solve further?

Try writing the for loop version first.

yes i have done using for loop
for(i=1;i<=n;i++)
printf("%d\n", i);
but i want to do it using recursion

Yep, and you even named the variables the same way. Implement the recursive version then. You just need to invert the loop condition to be your recursive base case (or alternatively, you can put the entire body of the function within the body of the if statement).

Actually, since you are only printing, you don't need to return an int, i.e., change rec's return type to void.

The function you have prints it backwards...
This is the function actually working.

Code:

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void rec(int n) {
    if(n > 1) {
        printf("%i\n",n);
        rec(n-1);
    } else {
        printf("1\n");
    };
};

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Quote:

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can anyone tell me whats the mistake in this code
thanks

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Code:

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n--;
 printf("%d\n",rec(n));

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Quote:

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if user enters 5 then output should be 1 2 3 4 5

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Code:

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#include <stdio.h>

---

Code:

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void rec(int i, int n) {
    printf("%i\n",i);
    if(n > i) {
        i++;
        rec(i,n);
    };
};

---

Code:

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int main() {
    int n;
    printf("enter no.");
    scanf("%d",&n);
    rec(1,n);
    return 0;
};

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Structure: don't do other people's homework before they have succeeded.

Quote:

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Originally Posted by Structure

Code:

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#include <stdio.h>

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Code:

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void rec(int i, int n) {
    printf("%i\n",i);
    if(n > i) {
        i++;
        rec(i,n);
    };
};

---

Code:

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int main() {
    int n;
    printf("enter no.");
    scanf("%d",&n);
    rec(1,n);
    return 0;
};

---

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Hey Thanks man. this code is working !!

Quote:

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this code is working

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Code:

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  rec(100,150);

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Code:

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void numbers(int one, int two) {
  printf( "%i\n", one );
  if ( one != two ) {
    if ( one > two ) {
      one--;
    } else if ( two > one ) {
      one++;
    };
    numbers(one,two);
  };
};

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Quote:

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structure:

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Recursion (computer science) - Wikipedia