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

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)
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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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*  *  * **   *****
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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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* * *   * *  ****  * *** *****  ** 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  * **   **    **** 
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}

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

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'