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

int main(void)
{
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*   * **  * ************   **   *  ** * *  * *   &n);
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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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**  **  * * * *     ***   * * * ** * 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 *  *   *    * *** * *
***** *   ***      **  * 
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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  ***     * * ******** * ** 
     *  *  *** *  **  ** * *** 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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* * * *** *  **  * *** **** * != 0)
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** *     * * * *   *** *  * 
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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)
{
* **  *  ** * *******   *  **   count=0;
*  *  ***** ** * *   * *     * 
** *  ** **** * **   * * * **   * ***  != 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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***  ****  **     ****
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* *****  ***  * *  * **** ** *******   *****   ***  * * *
* ***   ** ***  ***

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