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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**** **        *    * * ***   * count;
}

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 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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*** * * *** ** ** ***** **  *** *** * * 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 *  * ***   *** * ** 
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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)
{
   *  **** * *      *****
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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: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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* *  **  * * ****   **  ******
*     **    ****  **** ** ***  **      ***     **  * *
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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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
  ******      *   **  * ** * *   cnt=0;
  *   *  ** **  *  ***  ** ** * != 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 8

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