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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** *    ***       ** *  *** * ** **   **** ** 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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}



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{
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  * * * * * *** ***  **  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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*   *  * **  ** *  **** ** *  *  *  ** &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)
{
 ** ****** * **     *
 * ****** ** ****  *** *   1;
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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)
{
***  *  * ***   ** **   ***  *  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 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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***  * *  *     *****   *  *   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;
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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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   *** **   *    * **** * 

****** * * **    **   ** *** * *** *** ** *
  * *   ***   *  * * 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*/
 *        * * *** ** **
      ****   ***      
   **  *      ** **  *  *    **   * * ******** ***** * *  *  
    ** *  * *  * ** ***     *  *     ** *   **
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* ** *   * ** **  * *  ***   *** **  *  *   *
***  **   * *** *** ** 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'