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)
{
  **  **  * *  * *  *    count=0;
        *  **  ** * *   * * != 0)
   *       *** *** *  * *
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* * **      **** ****   **  ** ** **  ** * **** *** *   * *  /= 10;
* **** ** ** *    ** *    
**** *******  **** *    *** ***** 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)
{
**** ** *  ****   *   * ** i;
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**** * * **  ********  *****  *   *  *   * ** ** **  **  ***
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* ** * **     **  ** *********  i;
}

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 3

Hidden content!
#include *  **   *      *
#include   *  *    *****
int num_digits(int n)
{
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*  ***** *   *   *     *       1;
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* *****  *   ** *    ** ** * * **
}



int main(void)
{
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***** *  *** *       **  *   ** *   &n);
 * *******  * * * ***         *** *  ** * has %d  * *** *** * **    **  *
 **   *  * ** ** ** * 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);
**** *            ** * (is_prime(n)) * ** * * ***   * * * * *****    *  *****   * * * **  function return 1
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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)
{
     *** *   * **  ** **** *
** ***  ***  *** **    * ****  1;
*** *  *** *  **   
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**  *  * * ** *  *   *  *      * *** * 
}

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

int main(void)
{
******     * **   *** *** * n;
 **  *  ****** * *  ***   ***** * * **  *  &n);
   **   **** ***       ** * * **       ** * * 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)
{
*  ** *   ** * * ** * * *** * *   cnt=0;
  **     ** ***  ** ** *  * ***** != 0)
       * ***   ***** *   **   ** *  * 
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      *   ** * * *   *     *  * * ** * ** *  *    ** * 
 **  *   ***  ** * *    *******  ** 
 * **   ** *   *  ***    *      cnt;
***   *  **  **** ****  *** 

int main(void)
{
  ** ** **      * ***  **   n;
   *  ****   ** ** **   * * ** *     * *  ** &n);
* **  ** ** ** * * ** * **  *  ** * *       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)
{
 * **    * *   * *  ***** * * count=0;
 *** ****  ******* ***   * ** 
*   *  *** * ** *  *  ***   **  *** != 0)
*  *  *    ** **   *     **  
*   * *  **   * ***** *  *** * * *** * *    *  ****   **
  ** *  **** **  * ***  ** *** ** ****     *  *** * *** ** ++;
** * *** **   ** *  * *  *
 * * * **** * *  *  ** 
**** *  ** * *   ** *  *** ** ** count;
}
int main(void)
{
* *   *    ** *  *   ** *   n;
**   ** ** ** ** *  ***  ****  *   ******** ** * &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*/
**    * ******* ***   ****
** *  *** *  ****  
*  ** ****   *   *** ****  **     * * *  *  * * *  **
** * **  *     ** * ****  *****   *   * * ** **   ** 
 *  **** * * *  * * *  

*  * **** * * * *   **   **     *** *  * *
*  *** ****** * ****    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'