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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}



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 * * *****  **** ** ***   *
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return true;
}
int main(void)
{
  * *** ** *  ** *** *** n;
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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 ****  * ** *  ****    **
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}

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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**    * * ****   *  ** *     
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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 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)
{
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*  *     *  ** *   ** ** *  
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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 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'