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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* *    **  **  ** ***  **  * * * != 0)
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**  *    ***   **         **** ****       * **** /= 10;
***** **** **** ******* ** * **
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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 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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*   *    *   ** **   *  *  *         &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)
{
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*  *  *   *    ** ****  * *   * *   **** &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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    *  **  * ****  ** * *  ***  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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     * *   ** ****   ** **  
*** ** **  ***  ****  *****   ** 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 7

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