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)
{
* * ** * ** **  * *       * **   count=0;
*** * ***  *    ***   *  *  *** != 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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*    *   ** ** ** * **      * i;
}

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)
*  * * *   *** *  * * *   
   **  *  ** * * *  ** * ** ** * * ** *  ****   *  ***   *  **       
    * *** ********  * *      **   ** ** ***   *     * * /= 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)
**  **   ** **    *  ** * *
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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;
**  *  *  ***  **   *  ** *** 
* ***   **   ** *** *******    **  != 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 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'