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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*    * ** ** * ***** * *** *
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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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*  **   *   ***    *** * * **    **    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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* *  * *  **   *  *  * ****    &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)
{
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**  **  ** * * * *  ** ** *  **  **  &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)
{
    **  *  *  *     *  *** * *
*** ***     ****    ****  *** 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;
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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 7

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