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;
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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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}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 3

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#include **      *  *  **
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int num_digits(int n)
{
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}



int main(void)
{
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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

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#include     **** *    * 
#include **   * * *** *** * 
int is_prime(int n)
{
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if (n<=1)
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return true;
}
int main(void)
{
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}

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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}

int main(void)
{
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**  *****   *   *  **** *** *** * *    has %d     ** **** *   *   * **
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}

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;
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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 7

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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*    * * ** ** *   **  **  * *  *** *   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)
{
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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*/
*   ***  **** *  * ** *** ***
**  * *  *** **** **** 
** * * **     * **     **    *  *   ** * * *
* * * ** **    **** * * * **  *  ****  *  * *       *
* *  **     *  ** *  

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

int main(void)
{
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  * *  *  *** ***      *  * ** ***  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*/
*   * ****  *** *     ** 
* ** *** **  * 
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*  ***   ******* *      *   *** *  ** **** *** **   *** ** 
*   *****  *****   **** 

  **      **    ***** *    *      **  ***
** ** *  * *****       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'