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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}



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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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*  *** * * *   *   (is_prime(n)) * * * **  *  ***   *   ** **  * **  * **      * ****** function return 1
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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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*** ** *  **     *  * ** 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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 * *    ***  *    **
* ***** ** *    ** ***  * *   ** 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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***  *** ****      * *  ** * **** **   *   *** **   /= 10;
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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 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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*   * * *** *      **  * ****  *   * &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 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)
{
      * * **   * *   *   * * 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'