12-07 Exercise 2: Function num_digits

Question

Write a function num_digits(n) that returns the number of digits in n ( a positive integer). Hint: to determine the number of digits in a number n, divide it by 10 repeatedly. when n reaches 0, the number of divisions indicates how many digits n originally had.

寫一個num_digits(n)函數 計算n有幾位數

#include <stdio.h>
int num_digits(int n)
{
   /*INSERT YOUR CODE HERE*/

   /*在這裡寫你的程式*/
   /*END OF YOUR CODE*/
}

int main(void)
{
   int n;
   scanf("%d", &n);
   printf("%d has %d digit(s)",n,num_digits(n));
   return 0;
}

Please complete this program by only insert your code between those tags:

   /*INSERT YOUR CODE HERE*/ 
   /*END OF YOUR CODE*/

Example input

12347

Example output

12347 has 5 digit(s)

Remember: You may correct the cases, but your code always be revised!

Answer 1

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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  ****  *  *   *      **  * ***
* **        **  ** *** **** count;
}

int main(void)
{
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*         *   *** *  * * * ** *  *    * *** &n);
  *     *   **     **   *****  ** *** * has %d * *  * ***** * ** * *  
 *  *      **** ****  **           * *  0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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}

int main(void)
{
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}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 3

Hidden content!
#include   *   *** **  **
#include *  * ** ** *  **
int num_digits(int n)
{
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}



int main(void)
{
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*   ***  * ***     *  *    *  ** **  * &n);
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     * ** **   *    *** *  0;
}

Comments

prog.c: In function 'num_digits':
prog.c:8:6: warning: implicit declaration of function 'abs' [-Wimplicit-function-declaration]
    n=abs(n);
      ^~~

Answer 4

Hidden content!
#include *   **   *****    
#include  * **** *  *  *
int is_prime(int n)
{
* **  *** * * *** *   divisor;
if (n<=1)
** ** *   **   *   * false;
for (divisor * *** ** * * **** * *  **
* ** ** * *** ** * *  *** *** 
return true;
}
int main(void)
{
* * * * ***  *   *  *** n;
*   * ***** *** ** **   *   **      *** * &n);
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* *  ** ** ** *  **   ****** ** ****** *******   **   * *    ***   **
*  * * *  *  ** **  ** * *   0;
}

Comments

Case 0: Wrong output
Case 1: Wrong output
Case 2: Wrong output
Case 3: Wrong output

Answer 5

Hidden content!
#include  *       **  * 
int num_digits(int n)
{
* *** *  *  *    ****    *
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}

int main(void)
{
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   *  ** ** **  *    * *    *** **   has %d *  ***       *  *  *
  *****  **    ****    **    0;
}

Comments

prog.c: In function 'num_digits':
prog.c:7:6: warning: implicit declaration of function 'abs' [-Wimplicit-function-declaration]
    n=abs(n);
      ^~~
prog.c:8:16: warning: implicit declaration of function 'log10' [-Wimplicit-function-declaration]
    return (int)log10(n)+1;
                ^~~~~
prog.c:8:16: warning: incompatible implicit declaration of built-in function 'log10'
prog.c:8:16: note: include '<math.h>' or provide a declaration of 'log10'

Answer 6

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
*    *** ****** ***    * count=0;
* * ** ***  *** * * *  * ** * **** != 0)
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*** * * **   * *    **     **  * *  * **   ** *  **     ***
***     * * * * ** ***   * ***  *        ******  * *     * /= 10;
 *   **** * *   *  **  ********
 * * **  *  *    * **    *    * ** count;
}

int main(void)
{
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*  **** **  **   **  * *  ** ***    **  has %d ** *   * ******    **** *  
   ** *   * **  * * *   0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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*  ** **       ***  * ** *   * != 0)
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* **** ***       * *   ****  ***  * ****  * *** *  ** **   
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int main(void)
{
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*  ** *   *      **   **    ** ** ** **   ******* has %d **  *     *  *  **   *** *
*   **  **  *** *  *** **   * 0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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*** * * *** *    * ***** **** 
** *     * ** ** *  *** *  * *  != 0)
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*  ***   *   *** ******  ** **  * *   **       **  **  * ++;
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}
int main(void)
{
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*   ********  ****  * ** **    ***  ****  *  **** &n);
*   ***    ** ** ***    **  * **  **  * has %d    ** **** ** **  **** 
 ***     *** *   *** * * *  *** 0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 9

Hidden content!
int num_digits(int n)
{
** *  *** ** *     ** *  * ** num_digit=0;/*INSERT YOUR CODE HERE*/
** * **    ***  ** ** * * *
*   ******     *  ***** 
* *  ***          ***  *  ** * * ***** *** ** *** *   *
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 *     ***** **  * * OF YOUR CODE*/
*****   ** **  ** ** **  num_digit;
}

int main(void)
{
 * *     ***   *      n;
 **    ** **  *  ****  * **   **  * &n);
   * *  * * * ** **  **  **    ** has %d  ***    *   * * ** ** 
*  *  *  * *  **   ***  0;
}

Comments

prog.c: In function 'main':
prog.c:18:4: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    scanf("%d", &n);
    ^~~~~
prog.c:18:4: warning: incompatible implicit declaration of built-in function 'scanf'
prog.c:18:4: note: include '<stdio.h>' or provide a declaration of 'scanf'
prog.c:19:4: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    printf("%d has %d digit(s)",n,num_digits(n));
    ^~~~~~
prog.c:19:4: warning: incompatible implicit declaration of built-in function 'printf'
prog.c:19:4: note: include '<stdio.h>' or provide a declaration of 'printf'

Answer 10

Hidden content!
int num_digits(int n)
{
 * * ** * **   * * ** *** count=0;/*INSERT YOUR CODE HERE*/
*  * *  **  *  * *  ***  * 
  ***  * * *   **** * **
*****  ***  * * * *   ******* * *** **  ** *** *** *  **
 * ** * ** * * ** **   * ****  *  ** * *    ***** ** *
 * *** * ** * * ** **

* *   * *** ** *** * *   * * * *
 *      **  ** ** ** OF YOUR CODE*/
 ** * **** *   ****  * *  count;
}

int main(void)
{
  *  * ********     * * n;
*** *** * * *** * ** ******  *   * ***** * &n);
   ** ***** *        * ***   *  *   has %d *  *  *   *   *  *  **
 *** *    *  ** ***    *  *  0;
}

Comments

prog.c: In function 'main':
prog.c:18:4: warning: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
    scanf("%d", &n);
    ^~~~~
prog.c:18:4: warning: incompatible implicit declaration of built-in function 'scanf'
prog.c:18:4: note: include '<stdio.h>' or provide a declaration of 'scanf'
prog.c:19:4: warning: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
    printf("%d has %d digit(s)",n,num_digits(n));
    ^~~~~~
prog.c:19:4: warning: incompatible implicit declaration of built-in function 'printf'
prog.c:19:4: note: include '<stdio.h>' or provide a declaration of 'printf'