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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  ***    *** * *    *   * 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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** * *   **   *** ** *   * * 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 **** * * * * *  * *  * *   *  *
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return true;
}
int main(void)
{
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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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 *** ** *   *     *
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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)
{
******* *  ***    *  **** * *** 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)
{
 *** ** *  *   **   ** * ***  count=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 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'