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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}

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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}

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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* *** **  *** ****  *   *
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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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* * *** *   * **  *** **     * **  cnt;
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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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*  **  *  * **    **  ***   ***
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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 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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* ** * * ***  *** *    *  * *   *  *   * 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'