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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******  *        **    *     *** **    *    **   ** &n);
   *  ** ******   *  **   *  *** *         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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***    ***  ***    * *** *   * *  has %d   * **     ** **** *   
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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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**  * *  ** ** *  *  *** * * * * * * &n);
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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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            ***  *** ****** 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)
{
*** ***     ** ** **   **  
* *   * **  ** ** *   *    ** ****  1;
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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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*   * ** * *  ** **** **  ***
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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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****   * * * *** * * *** * **** *   *  ***    *  *  &n);
*  * * * ** * *** *** * * ** * *  * 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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** *   ** ** **** ********** *
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}
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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***  *     * *   * **** *** **      ** * ** *    ***    *
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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*/
    * * **      ***    **** 
* *****  * *   *** * *
 **    ***  * ******  * *** * * ** ***** *   **** ***
*  **    *** ***   **      ** * * *  **    ** **   * *   ** ***
*   **  * ** ** * **

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