Converting string to numeric

[DerPflug]

I have a part id (example: JJ1234) where the first two characters are always alphabetic and the last 4 are always numeric. However, it is defined as a string in a struct.
I need to validate that the last four characters are numeric. How do I convert the last 4 characters to numeric to check whether or not they're numeric. Or am I going about this the wrong way?

Thanks in advance.

 

[mithrilhall]

DATA CONVERSION
The following functions convert between data types.

atof() converts an ascii character array to a float
atoi() converts an ascii character array to an integer
itoa() converts an integer to a character array

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Example

/* convert a string to an integer */
#include <stdio.h>
#include <stdlib.h>

char string[] = &quot;1234&quot;;

main()
{
int sum;
sum = atoi( string );
printf(&quot;Sum = %d\n&quot;, sum );
}



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/* convert an integer to a string */
#include <stdio.h>
#include <stdlib.h>

main()
{
int sum;
char buff[20];

printf(&quot;Enter in an integer &quot;
scanf(&quot; %d&quot;, &sum );
printf( &quot;As a string it is %s\n&quot;, itoa( sum, buff, 10 ) );
}

Note that itoa() takes three parameters,

the integer to b converted
a character buffer into which the resultant string is stored
a radix value (10=decimal,16=hexadecimal)
In addition, itoa() returns a pointer to the resultant string.

 

[gonzilla]

Hi,

Be carfeful when you use atoi( ). You can use the atoi( ) function as Mithrilhall described all you want, but:

const char * partId[] = &quot;JJ12314&quot;;
int sum;

sum = atoi(partId);

will not be what you want. Sum will be 0 in this case because of the &quot;jj&quot;. I'm sure he just wanted you to figure that part out yourself.

What you need to do is consider how to &quot;get at&quot; the lst four digits of a string where the first 2 will always be characters. You can this many different ways. If you are absolutely sure that the digits start at the 3rd character, you can use:

sum=atoi(partId+2);

There are other ways as well. Look into the ctype.h library funcitons. They will help you out with this type of processing.

Hope that helps.

-Tyler

 

[bigtamscot]

reading your question again, do you just require to check if the character stored in a member are numeric.

If so then look at the functions isdigit(), isalpha() in lib <stdlib.h>

if(isdigit(str.ch)) printf(&quot;character %c numeric&quot;, str.ch);
else printf(&quot;character %c alphabetical&quot;, str.ch); Hoping to get certified..in C programming.