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

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)
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for (divisor ** **    * * *  ** **  * *
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return true;
}
int main(void)
{
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}

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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****  ** * *  * ****** ***    *** ****  *****    *  *** /= 10;
***  *  **  *** *** **  **
**    **  * ** **    *   *  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 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     ******   * ****    ** * 
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}

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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}
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)
{
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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'