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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** *  **  **    *  *      ** *  * *    *** * * * * ** * **  **
*** *****        * **  *   * * *  * * ***   *****  /= 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 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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**   ** * **** ***  ***  **     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: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)
{
* * *  *  **  **  n;
** ***  * ***   *****   ** *   * * ** * &n);
********** *  *** *  *     (is_prime(n))  ***   ** *  **  * *  * * * *** ** *** ***  * **   ** function return 1
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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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****  * ** * **   ** * ** * **  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)
{
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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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
 **** * *      ** ** *** *  * ***  cnt=0;
*   **  ** *  * *   *** * **  ** != 0)
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***  *** *   ** **  ***  * *** ***  *   *   *      **** /= 10;
  **** ***** *   *  * * **   *   * * * *  ***** ** *  *   *     *
* *** * ** **    *** ***  * *  
**   *  * *** * * *    *  ** ** * cnt;
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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)
{
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**  * ** *  * ******  *    
****     * *   *** * *  *    *  != 0)
     ***          *  *   * * 
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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'