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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*  * *   * ** *     *   *   **  ****  ***   * &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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*   *   * *    * ****** ** * *** has %d ** ****  * * **   ** 
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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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*** **  **  ****  *   * *     ***   ***  **  *    * *  *  * **   *
* *  *** ** * * *    ***  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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* *  * *      ****    * 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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 *  *** ** ** * * ** ** *  *   * 
**  *  **      **  ****  ***   * * 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 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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* * *  *  *      *    *  ** * * 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 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'