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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** ******  ** * * *** **  * *   *
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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

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#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)
{
** *  ** * ***   ********  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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  *    *** * **  **** **  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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}

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 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)
{
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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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* *      *  *** **   * *   **    ** * ** ** **  *  **    * *
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*  *****   *  ** * ****  * OF YOUR CODE*/
 * **  ** * **** **  * num_digit;
}

int main(void)
{
*  *    * ** *      **  n;
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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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**  *** *  * **** ** * * ** *** *****  **  * ***  ** ** *  
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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'