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

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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** * ** * *     ** * ** *  ***  ****  *  &n);
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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)
{
*    *   ***  * **      n;
 * **** * *** **** *    ** *   ** *  &n);
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* * ** *     ***  **    * **  **  *    **      *  *****  ** *** *  *** * *** * *    **** * **  **  * *  *  *** *        **   ***   **     * *   * * * * * ** function return 0
  ** * *  **   *  *  **  ****     ***    ** **** *  *     *  ** * 
 * **    **   **   * *  * 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)
 *  *  ***** ** * ** * *
* **     **** *  *** ****  *** **** * * *** * * **   *  *  ** 
* *  *   * **  * ***  *  * *  *     ***  * * * **  /= 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;
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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)
{
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** **   *  **** *   *   *
*   * **    *  ******    *  ***  ** != 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)
{
****  **  * **  **** *   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'