Go4Expert - how to avoid to printing the value of charecter in C?

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how to avoid to printing the value of charecter in C?

Hi Friends,
I wrote a program in c to print a table for ant in teger as shown below

/**----------------------------------------**/
int a,b,c;
printf("Enter the value of a\n");
scanf("%d",&a);

for(b=1; b<= 20; b++)
{
c=a*b;
printf("%d X %d = %d\n",a, b,c );
}
/**-----------------------------------------**/

This program is working fine,when i give input as a number.

However,

[COLOR=DarkRed]in case,the given input is a charecter,[/COLOR]
Then it is showing some different output.

Re: how to avoid to printing the value of charecter in C?

Thats because the character when converted into ASCII and multiplied will be numbers not as per expectation and so its giving unexpected output.

Re: how to avoid to printing the value of charecter in C?

Hi Shabbir,
Thankyou very much for your reply.
Now what is the solution?
how can i use the function "isalpha()"
to avoid the above problem

Re: how to avoid to printing the value of charecter in C?

Code:

   char c;

   scanf( "%c", &c );

   if( isalpha(c) )

     printf( "You entered a letter of the alphabet\n" );

Re: how to avoid to printing the value of charecter in C?

Check This code ( I only use cout and cin instead of scanf() and printf() )

Code:

#include <iostream>

#include <cstdlib>

#include <cctype>

using namespace std;



int valid_data(const char *data)

{

    int i=0;

    //TO Check -ve Number

    if(data[0] == '-')

        i++;

    //To check if only '-' sign is their

    if(data[i] == '\0' )

        return 1;

    while(data[i] != '\0')

    {

        if(!isdigit(data[i]))

            return 1;

        i++;

    }

    return 0;

}



int main()

{

        string n;

        cout<<"Enter Value of n : ";

        cin>>n;

        if(!valid_data(n.c_str()))

        {

            int a = atoi(n.c_str());

        for(int i=1;i<=20;i++)

            cout<<a<<" X "<<i<<" = "<<a*i<<endl;

        }

    else

        cout<<"Invalid Value";

        return 0;

}

If you want a simpler code you read this about aoti() function

Quote:

About aoti(const char *)
On success, the function returns the converted integral number as an int value.
If no valid conversion could be performed, a zero value is returned.
If the correct value is out of the range of representable values, INT_MAX or INT_MIN is returned.

You can check whether returned value is zero or not. If it is zero then you can display message. "Invalid Value". But here we cannot check if user has entered zero (0) as value. If user has entered zero (0) as value then also your program will display "Invalid Value". Hence i do not suggest this.

Regards

Re: how to avoid to printing the value of charecter in C?