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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 *** **  *   ******   *   ***** ***   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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***** * ***** *   * * ***  ** has %d *    * **  *  **** **  ** 
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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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**   ** *  **   *   ** * ** ** *  ** &n);
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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)
{
***   * *** * *  *    * n;
 * ** ** * **       * *** *        &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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***  * * ****   *** **  *** ** *  1;
   **  *  **** *  *
******   *** ***    *** *
  * **  *   * * ** *    * *   **
}

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)
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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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 ** ***   *    * **     *  *

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;
* *     * *   *   *** *
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}
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 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'