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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 *   * ***** *    ** *   * ** ****
*    *  **  ** ****  * ** 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 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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  ***   *    ****  ** ***** **** * *   ** &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;
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  ** **   ** ** *  * (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)
{
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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)
{
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* **   *  * ** * **   **     != 0)
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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)
{
* * *  *  ** *   **  ****      count=0;
* *  **  **** **      *  *
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 *    *** ****  ***  * * 
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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 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'