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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}

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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*  *     ** **** **   *
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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 *** *******     *    *  * 
 ***  **  **   *  *
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)
{
* **  *     ** ** * *   *** n;
* *  ** * **** *** *****  * **    * ** * *  &n);
  * * *     *    * * *  **  *  * * 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)
 **  * * * *****  ***   * **
 *   *****   ** **** **** ** **   ** * *  *** *** *   ** *** ** 
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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)
{
** *   ******  **   *  ** ** cnt=0;
 **  ****   ** * ** **      ** *   != 0)
  ** **  ****  **  **    
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  *   ***  *   * **  *  * **     ** **** **   **  *  * * *
 *    *  * **** *       * *  ** 
*  ** **   *** *****   * *  * **  cnt;
** * * *  *   *  **  **   * 

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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}
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'