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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 * ** ** * ** ** ** * ** **    *** * *  * 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)
{
   **  * ** ** **  ** 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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*  *  *  ****       ** **  **  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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* **    ** *** ****   ***

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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** ** *    *** * * **** * *****   * ***   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'