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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* ***  * ** *  ** ** **  ** * != 0)
**       ** * * *** ** *   *  
* *  * *  * *  *** **  ** * * * * *****   * **** *  *****   
** * * ** * ** * ***  ***   ****  *  *   *   *  * * /= 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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*  *** *  * *  ****   **    *   *    **   *   
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**   *   *** * * *** *   * *  i;
}

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         ** **** ** **** * 
***     *** ***    *       **
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)
{
 * ** **  * ***  **   **    count=0;
   *   *  **  * ******* * *   * * != 0)
** * **   **   ** ** 
* *   * ***  **  **  **    *   ***   ****      ** ****
* **    *  **     * **** **   * **  ** * ** ** * *** * /= 10;
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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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
 *  * * * *  **    * *  *  *  cnt=0;
* * ****** ***       ***         *  != 0)
*** *  ** *** ***   * ** *  * *
*  ** ****  *** * * ***  * * *  * *  ** *  * **    * *     /= 10;
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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;
** **   * * ** * * ***  
*** *  ******* *  *** *  **   ***  != 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'