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 ** * ** *     *   * **** *
  ****   ***   *     **  **** 0;
}

Comments

Case 0: Correct output
Case 1: Correct output
Case 2: Correct output
Case 3: Correct output

Answer 2

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#include <stdio.h>
int num_digits(int n)
{
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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 3

Hidden content!
#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)
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for (divisor ***     *   ** ****    *   
** * *    **  *     * * *  *
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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}

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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*  *  *** *   * *  ******** *** *
* *****  ****** *  * *  ***** 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 7

Hidden content!
#include <stdio.h>
int num_digits(int n)
{
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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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}
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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** *   ** * *** ****   * *  **** * *    **   ** ****
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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'