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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}

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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****    *  **  ** * * ** 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 ** ** **   *  **     * **
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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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*  ***    * ***   * * 
**  *** * ****    **  * *  ** 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 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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*    *** ***   * **   **  *  **  ***       *      &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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***  * *    ** *     *   ***   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'