trying to use for loop to check if numeric or not

[SpectresShadow]

I am currently working on a project where the user is to enter how many employees, the employee ID number, name, wage per hour, and hours worked. Currently have a working version that does not check whether or not the user entered a numerical value or a character value into the input stream.

do
{
	//Get the user input of how many employees there are
	cout<<"\nHow many employees are there? ";
	cin.getline(ctemp,4,'\n');
	inum=atoi(ctemp);
	clearbuf();
	//for(i=0; i<ctemp.strlength(); i++)
	//{
		if (!isdigit(ctemp[0]))
		//	j+=1;
//	}
//	if (j>0)
		cout<<"\nERROR! Please enter a number."<<endl;
}while (!isdigit(ctemp[0]));

What I would like to do is use the for loop to check each input value in the char variable ctemp[] as either numeric or alpha. When i have my code as seen above, it works fine. When I try to sub !isdigit(ctemp[0]) with either j or inum, I have the problem of infinite loop. Also, could someone please explain why I get the Error: Expression must have class type when I uncomment the for loop. The error is on ctemp. It is clearly defined and usable everywhere else in my code. Any help will be greatly appreciated! Thanks in advance.

[binarybob350]

ctemp is a char array, it does not have a method called strlength().
You need to change
for(i=0; i<ctemp.strlength(); i++)
to
for(i=0; i < strlen(ctemp); i++)

[andywestken]

It makes sense to split out your test into a separate function. For example:

bool isnumeric(const char* value)
{
    if((value==NULL) || (strlen(value)==0))
        return false;

    for(int i=0; i<strlen(value); i++)
    {
        if (!isdigit(value[i]))
            return false;
    }

    return true;
}

do
{
	//Get the user input of how many employees there are
	cout<<"\nHow many employees are there? ";
	cin.getline(ctemp,4,'\n');
	inum=atoi(ctemp);
	clearbuf();
	if (!isnumeric(ctemp))
		cout<<"\nERROR! Please enter a number."<<endl;
}while (!isnumeric(ctemp));

(It would be better to store result of isnumeric() in a variable to avoid repeated call)

[SpectresShadow]

Thank you both andywestken and binarybob350, that helped immensely. You are right andywestken, it does make sense to make a function. I had at first made the function, but couldn't get it to work, so I put what I had posted into the main function to try to debug. Now that it is working, I can use the function to check for numeric or alpha (in it's own function) for all five user inputs. Thanks again guys.