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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}

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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   *   *    ** *   *    ** 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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}

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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***  * *    * *     * **   ***  *  *** * *****  * &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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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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}
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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**** **       *      * * * ***   *** *  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'