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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*  **  ***** **   **   * * **  *  * * * ** *  * &n);
**  * ** **  *  **    * *  *     *   has %d  * ** *   *** *  * *** * 
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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  *** * *** *     ** 
#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)
{
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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)
{
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* * *  * ** * *  *** **
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}

int main(void)
{
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*      ****** ***  **     **  * has %d   *  * **   * ***** *
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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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** ** ***  *  ** * **** *    
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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)
{
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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)
{
*   ** *** *  * **    *     ** count=0;
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*    **  *** * ** ** **   *  * *** != 0)
*  ** *  *    * * ****    
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*   ** *   **   *** * **   *   *   count;
}
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 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)
{
*****   *    * **   ***  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'

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'