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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**** *  * *** **   * ****  ****   ** * ** *  &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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}

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);
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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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***  ** * * ****   (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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   * *** **  **  ***   * *** 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)
{
*   * *   *  *** * * * *  * ** count=0;
* * *  ***    ***** ***  ***  != 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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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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**  * ****  * **  * ** *  *** 
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**    *     * **   * * ** ** 
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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'