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)
{
*** **  ***  *   ****** * *** * 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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}

int main(void)
{
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}

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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}

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);
 *   **    * * **  * (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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}

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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**     ** * * ***    **** * 
***   *  * * *     ***  *** *  *** * 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 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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*** **   *  ** * * *** *** **        ***** * &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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*** * ** ** *  *  *** *  *** 
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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'