Test if a var is a integer 1

[bateman23]

Hi everybody,

I know in VB there is the function isinteger() to test if a variable is a integer. Is there such a possibility in C++?

I'm searching for a function, or another possibility to test if a variable, or better a user input is an integer.

Thanks in advance,

bateman23 aka Daniel

---------------------------------------
Visit me @:

http://www.daniel-purucker.de/

 

[Zyrenthian]

to test if user input is an integer just use

strspn(inputBuffer,"1234567890&quot == strlen(inputBuffer)

in a conditional statement.


matt

 

[bateman23]

Ok - I should have said, that i'm very new to C++ ;-)
,so.....

my code actually looks like this:
cout << &quot;Type a number :&quot;;
cin >> number;

Now, here i have to check if that really is a number.
the code above doesn't work - at least i can't get it work.
Do i have to include a library, or does the varible has to be a special type? (now it's int)

Thanks,
Daniel
---------------------------------------
Visit me @:

http://www.daniel-purucker.de/

 

[Zyrenthian]

Sorry.,.. here is a sample

#include <string.h>
#include <stdio.h>
#include <iostream.h>

int main()
{
   char buffer[32];
   cout<<&quot;Type a Number: &quot;;
   cin>>buffer;
   
   if(strspn(buffer,&quot;1234567890&quot;) == strlen(buffer))
   {
       cout<<&quot;Thank you for entering a number\r\n&quot;;
   }
   else
   {
      cout<<&quot;You need to learn what a number is!\r\n&quot;;
   }
}

That is the basics of it. This should compile if you just cut and paste... unless i forgot a semicolon somewhere

Matt

 

[bateman23]

wow, thanks a lot for the very fast (!!) answer.
And even everything works.... a big star for you.

But - am i right - you can just perform this check with a
char-type ?
char buffer[32];
cin>>buffer;

Thanks, you helped me a lot
Daniel ---------------------------------------
Visit me @:

http://www.daniel-purucker.de/

 

[Zyrenthian]

Theoretically, what is actually going on here is your looking at the ansi equivalent characters for the value. To pull the value out of the buffer, you will need to call atoi(buffer) which will return the value.

with cin, any base type can go after it.


int val;
char c;
char str[32];

cin>>val;
cin>>c;
cin>>str;

are all valid. The problems that occur is when the user enters a string into val.

Matt