using scanf just for numbers, not allowing letters or characters

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C#

void FillArray(int m[35])
{
    int i;
    for (i = 0; i <= 34; i++)
    {
        printf("Enter Mark for Element[%d] :", i);
        scanf("%d", &m[i]);
        while (m[i]<=1 || m[i]>=7)
        {
        printf("\nError! Mark should in range of (2 to 6).\n\n");
        printf("Enter Mark again for Element[%d] :", i);
        scanf("%d", &m[i]);
        }
    }
}

in this code i m taking nubers between 2 - 6 but when i enter a letter sticking to code which parameter i need to just use numbers mean not allow letters or characters thank you

Posted 11-Dec-13 0:30am

ivaylov

Updated 11-Dec-13 0:31am

v2

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CPallini 11-Dec-13 8:01am

Why are you using while? if would be enough (just curiosity).

3 solutions

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OriginalGriff · Answer 1 · 2013-12-11T00:44:00

Solution 1

scanf can't prevent the user typing anything: all it does is read what the user typed and try to process it according to the format you provide and return a value which says if it passed or failed.
If you need to prevent the user typing invalid characters, you need to use your operating system / compiler specific functions to read each character as it is typed and accept or reject it at that point.

Posted 11-Dec-13 0:44am

OriginalGriff

Comments

ivaylov 11-Dec-13 6:49am

can you give one sample if user input letter or character it gives error and re-enter imput again

OriginalGriff 11-Dec-13 7:29am

Character-by-character checking is not parts of "standard C" - it's implementation depends on the compiler / OS you are using, so no I can't.

The only solution which uses standard C functions would be to read the whole string as a string, process it to check it is entirely valid, and report an error - but I don;t think that is what you are looking for.

User 59241 · Answer 2 · 2013-12-11T01:29:00

Solution 2

AS Griff says you need to go to a lower level than scanf. I can't help mentioning how useful Google is. Try this and ignore the 2 vote:

Rread a number input from the keyboard and then put each of its components in an array[^]

Posted 11-Dec-13 1:29am

User 59241

Updated 11-Dec-13 1:32am

v2

CPallini · Answer 3 · 2013-12-11T01:57:00

Solution 3

Quote:
scanf("%d", &m[i]);

That is not the correct usage of scanf: you should always check its return value, that is:

C

if ( scanf("%d", &m[i]) != 1 )
{
  // handle error.
}

Posted 11-Dec-13 1:57am

CPallini