4 replies to this topic

[debug]

hi, i want to know in c++ how can we extract things we want from a string. for example, if a user input 3434dfgrs3345, the output will be 34343345 instead of the char. :)

[v0id]

Look at this:

#include <iostream>
#include <string>

std::string ExtractNumbers(std::string Source)
{
	std::string Destination = "";
	
	for(int i = 0; i < Source.length(); i++)
		if(static_cast<int>(Source.at(i)) > 47 && 
		   static_cast<int>(Source.at(i)) < 58)
			Destination += Source.at(i);
	
	return Destination;
}

int main()
{
	std::string MyStringWithChars = "3434dfgrs3345";
	std::string MyStringWithoutChars = ExtractNumbers(MyStringWithChars);
	
	std::cout << MyStringWithChars << std::endl;
	std::cout << MyStringWithoutChars << std::endl;

	return 0;
}

This could probably be done with a stringstream as well.

[TkTech]

Look into the Regex library set. It can be used to extract anything from anything using simple calls. However, using functions like the one void listed above works perfectly for what you (seem) to want.

[debug]

thank for the reply. got another question to ask. how to change the below code into a function?

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

int main()
{
char myAddress[100] = {0};
int i;
cout <<"Enter the address:";
cin.getline(myAddress, 40);

for(i=0; i<100; i++)
{
if(static_cast<int>(myAddress[i])>=48 && static_cast<int>(myAddress[i])<=57)
{
cout<< myAddress[i];
}
}


return 0;
}

[v0id]

I don't know what of the code you want to be in a function.
I don't know if you have to use C-strings neither, because if you're using C++-strings, it would be easier for you.

#include <iostream>
#include <string>

int main()
{
	std::string myAddress;
	std::cout <<"Enter the address: ";
	std::getline(std::cin, myAddress);
	std::cout << "My address:        " << myAddress << std::endl;
	return 0;
}