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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}

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 *   **   *   **  
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int num_digits(int n)
{
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}



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{
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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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*** ** **  * *  ** *  **  **      **   &n);
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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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*  * *  *  * *** *  *** 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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}

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)
{
***     **  ****   **  *   cnt=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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}
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)
{
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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'