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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***    *  **  **  *****  ** *   ** ** ** *  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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}



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{
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*  * *    * * * * *** **    0;
}

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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}

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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***    **  **** **      * *****  ***  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)
{
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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 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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****   * **     *    *****    *  *    **  * &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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**** *  * **  **
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****  *         *  * **  *  * ** *   *  *  * *   ***
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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)
{
     **   ** ** * * ** ** * 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'