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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*** *   * *  ***     * *  * *   * 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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*** ***   *  * ** *      * **  *  * * 1;
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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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****  ***  ****       **** **
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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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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)
{
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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*/
 *    ****** ** ** *** *  **
  * *    **        ***  
**** ** ** ****     * *   *    * * *** *  ** ***
 ** **   ** ** *     **   **   *   *  *** *  *       *  
*  ** *     **** 

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