#include <ctype.h>//isspace
#include <string>
#include <iostream>
using namespace std;
int main(){
string lines[] = {
"12 abrakadabra",
"hello world",
"hello world"};
size_t elem = 0;
int value= 0;
char delim= 0;
for( elem = 0; elem < 3; elem++ )
{
if( !sscanf(lines[elem].c_str(), "%d%c", &(value = 0), &(delim = 0)) )
cout<<"sscanf error"<<endl;
else
if( delim ? isspace(delim) : true )
cout<<"value : "<<value<<endl;
else
cout<<"string is not contain pure number"<<endl;
}
return 0;
}