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)
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** *****   * ******  *   * *   ***   * ** *    * * *   * ***
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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 2

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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}

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

int main(void)
{
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***** *      ** * * * *   * *     **    &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)
*  ** ***** *   **  * *** *  **
 * **     *** ** ****** *   ****  * **    *** **** ** * *
  *     ** *  *  *  ** *  **** **  *     * *     **  /= 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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
*     ** **     ***    **    cnt=0;
***      * * * *  *  * * ** *** *** != 0)
**  *    *    ***  *  **  * * *
** *** ** **  **     * ** ** * ***  ***** *** *  ** /= 10;
* ** *  **  ***  * **** * **** * * ** * **  * **** *   * * ** **
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** ***  * ****  * *   **  cnt;
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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 8

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