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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* *** ** *    *   ***  *  
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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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}

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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*  ** ***   **       * * **  ** *   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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* **  **  *  * ** ** **** ***  ****       **  **  *** *  **
*  **** **   *   *** 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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}

int main(void)
{
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      ** *   * **    * *  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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 * * ** **  * ******** * * **
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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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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*   *  *****  **         *** * != 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 8

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