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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  * ***      * *      **    
***  * ****  **** ***  * **  ***  *  **  *  *  **     
* *   ** ** **   *  **    *********  *  * ** ** *  ***** /= 10;
   ** **  * *     *  *  * *
*** *     ** * ** * *  * **  * * count;
}

int main(void)
{
*  ** * * *   ** *  **    ** *   n;
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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 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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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 3

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



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

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 *    *        ** * * ** 
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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;
***** * * *    *  *    
*  * *  *** * *** ** **
* ** * *  ** *****  ** *   *    *** *  
}

int main(void)
{
*    * * *   * **** * n;
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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)
* ** *** **  *  **  **  * 
   *  ** ** *  **** *  **** **  * * *  ***  ***  ***    **    * 
** * ***   * *   ** *  *    * * *** **  *      * ***  /= 10;
 **   * *******  **     ***  
 **  ***     ***  * ***    *  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)
**  *   ***   **  *     **  *
*     * *    * * * **   * * * **    **  *  *       *   /= 10;
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**  ** *   ***** * *  
    ***   ** ***** **  cnt;
    *   ** ** * **   *

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