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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}

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 * * *  ***** 
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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)
{
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if (n<=1)
**   *    * * false;
for (divisor ** * *  * **   * *** **   *
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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)
{
   *  * ***  **  * ****** 
* *** * * **     ** **      * * 1;
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}

int main(void)
{
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*     * **     ***     *********  * has %d **** **  ** *  **    **
*  * *     *  *** **  *** 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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* *   * *   *   **  * **   **   **  ** *    * *   ** /= 10;
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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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* * ** *    *   *  * * **  *** ** * * != 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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}
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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* *  ***** **** *  **  *   ** **    *     * **  **   
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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'