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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**    * ** *  *** ** * * **** **  * **  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

Hidden content!
#include      * * *   * *
#include  *  ***  *** *****
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

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);
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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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}

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)
**    * * * *  *   *  ** 
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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)
{
** ***   * *   **** ***   *   * *** cnt=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 8

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

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