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;
****  * ***   * **   ***    *
* **      ******       **   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  ** ** *  **  
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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: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);
*    *    *   * *  *  * (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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}

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)
{
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*  ** **** * **   ***** ***** * *     * != 0)
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*  * *     *   *   *  **    
*      *  ****  ** ***** * ** count;
}

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 7

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

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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*  * * *  ***   * *** *  **
*   * *** * ** ** ****  * != 0)
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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 9

Hidden content!
int num_digits(int n)
{
**** *  *    *  *   * num_digit=0;/*INSERT YOUR CODE HERE*/
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** *   *   * ********
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 ******** **  ***       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*/
 ** * * *  ** **  **     *
** *    * ****   **  **
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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'