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

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 3

Hidden content!
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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: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 *    *  *        ** ****  
**** *** ** **  *    * *
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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*  **      ***   * *     ** ***
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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 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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** * * ***** * ***  *** *  ** 
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**   * ***    * ***** ** *      count;
}
int main(void)
{
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**** **   ****   ***  * *  ** *  *    * &n);
*  *  ******      * * *  * ** **  ** *** has %d **  **  ******* 
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}

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*/
* ***** *  *   * *  ***
***   **   *  *   * * 
*     *     ** *  ** *****  *** *     *  * ***
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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'