how to do the is numeric ?

[lalabear]

how do u do the if statement for numeric lie:
string abc;
if(abc = numeric)
cout << "abc is numeric";

pls giv me the code thx pls also inclue all the stuff like #include<iostream> coz is scared i confuse thx u greatly

[webcomplete.com]

Originally Posted by lalabear

how do u do the if statement for numeric lie:
string abc;
if(abc = numeric)
cout << "abc is numeric";

pls giv me the code thx pls also inclue all the stuff like #include<iostream> coz is scared i confuse thx u greatly

Here is the answer to your homework:

#include <iostream>
#include <string>
using namespace std ;


const bool IsNumeric(string a_Str)
{
	// COPY a pointer to string
	const char * l_Str = a_Str.c_str() ;

	// ITERATE each character in the string
	while( *l_Str )
	{
		// CHECK if current character is non-numeric
		if( !( (*l_Str)>='0' && (*l_Str)<='9') )
			// FOUND non-numeric
			return false;

		// NEXT char in string
		l_Str ++ ;
	}

	// RETURN is numeric = true
	return true ;
}

void main()
{
	string l_Str ;

	l_Str = "123" ;
	if( IsNumeric(l_Str.c_str()) )
		cout << l_Str << " is numeric." << endl ;
	else
		cout << l_Str << " is NOT numeric." << endl ;


	l_Str = "one hundred twenty three" ;
	if( IsNumeric(l_Str) )
		cout << l_Str << " is numeric." << endl ;
	else
		cout << l_Str << " is NOT numeric." << endl ;
}

Of course this doesn't handle formatted numeric like : 1,200,000 or 100.00 - but its just homework, im sure the professor isnt looking for a million dollar code - did you say your majoring in computer science?

Glad I could corrupt you

[Feis]

minor quibble, but when checking whether the character is a digit you can use the isdigit() function from the ctype lib(you'd have to #include<ctype.h>). its a boolean function, so you could just change this:
if( !( (*l_Str)>='0' && (*l_Str)<='9') )

to this:
if( !(isdigit(*l_Str)))

The ctype lib has a bunch of functions for checking your input for alphanumeric, lowercase, numeri, alpha, etc. so its pretty useful

[webcomplete.com]

Originally Posted by Feis

minor quibble, but when checking whether the character is a digit you can use the isdigit() function from the ctype lib(you'd have to #include<ctype.h>). its a boolean function, so you could just change this:
if( !( (*l_Str)>='0' && (*l_Str)<='9') )

to this:
if( !(isdigit(*l_Str)))

The ctype lib has a bunch of functions for checking your input for alphanumeric, lowercase, numeri, alpha, etc. so its pretty useful

no arguments.