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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**    *****  * ** ***   **    *  *  *   &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  *  * ** * ****   ****
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return true;
}
int main(void)
{
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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)
{
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  ******* ** **  ***   ***** *  * != 0)
* * *** **   *  **  *  
* ** ** * * ** **   ***  *  **  * **** **  ****** ****
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** *    *** ***  ****  *  *
   ***   ****  **** *   * count;
}

int main(void)
{
*    ***      *  *        ** n;
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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)
{
  ***   * **         *** * **   cnt=0;
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* *  * ** ** **   *      * * 
*** * *  ***   *** *****  * ***   **  **** *  ****  /= 10;
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**     *  *  ****    * *  **  
* *  ****    ** *  **     *  *  cnt;
**  **  *   ** ****   *  

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 8

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
**     * *** * **** ***    **  count=0;
 *  *  * ** *  *     
**  **  **** ** * *  ** **   * ** != 0)
**  * *** *******         *  *
*****    **     *     * *   **    ** * *** ** *  **    
***       ***  ***  ***   * * *   *  ** *  *   * ***  * ***    ++;
   * **  *  * * * *  * ** *  
**    * ** * **       * 
**  * ***   *  * **  *  **  **   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 9

Hidden content!
int num_digits(int n)
{
**         *****  **   *  num_digit=0;/*INSERT YOUR CODE HERE*/
*  *     * ** *  * **  **
 *   ***** ** ***  
*  *  *****  * ** * **   ** *  ** ** * *  * *  *
**     **   *  * ** ** *****   ****  *** ** * * **  *** 
** *** *** ** ** * ***   * * 

 *  *  * *  *  **    ***  * *     **
**   ** * * *     **  OF YOUR CODE*/
*** *  *  * ** *  *  * num_digit;
}

int main(void)
{
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 * * *  *  **     *  **  *  *  ** **   &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'