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)
     ***  ** **** * ****
*  ** *  *  *  * ** *   ** *  ***  * **   *** ***** **** * 
  *  *   * **  *   * *  * ********* *   * ** **  ** **  /= 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 2

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



int main(void)
{
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 ***  * **   ***** ***   * * * **    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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**  ****  *  * *****   *  *   **       &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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*  ** *    *** * * * * ****  
* *  *** **  * *   **    **   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)
{
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  *  *** ** ** ** ** * *** * != 0)
**    * * *    ***       ***** ** 
* ***    *  * **   ** *** * *** * ** * ***  **** * * *  ***   /= 10;
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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 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
   * *  ***  ** ** ** * *  * * count=0;
* * **   ****** *     ** *
* ***  **** *   *  *  *** *** *** != 0)
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   *  *** * ** ** *   ** **
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** *     **  * *     **  * * 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 9

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

*      *  *      *       * *** * * * * *** 
 *  *** *** *****   *  *   * OF YOUR CODE*/
 *    *   *  *  ** *****   num_digit;
}

int main(void)
{
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*   **   ****  ******** *   ** **  *   ** &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'