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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}

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 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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*  *** * ***  **  **   * ***** ** **    &n);
*  * ***  ****   ** **  *  *** 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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*** **   *****    * *** * * **  ** *    * &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)
{
****  * ***    **  **  
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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)
{
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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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*    *     ***** *   ** *  
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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)
{
* *  *   ** *   ** ** *    **  *  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*/
  *   *  ** *  *** **   *   
**    **    **  * * *  * ** 
* * * ** ** **     * ** **   **** *******   **** *
 ****  * *  *   *   ** ** ** **  ** *   * * * * *
* * *       ** **  ** *

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