strings

[zaac]

hey,
ive been stuck on this for a while, it should be easy,but i just cant get it.

what im trying to do is take a single digit from a string of digits and convert it into an int. heres my code so far



#include <sstream>
#include <iostream>
#include <string>

using namespace std;

int main() {
string str = "73167176";
int i = 4;
int num1;
istringstream buffer(&str[i]);
buffer >> num1;
cout << num1 << endl;
}


the problem with this is that i get the number 7176 instead of 7.

if i pass in str[i] instead of &str[i] i get en error "invalid conversion from ‘char’ to ‘std::_Ios_Openmode’"

how do i fix this problem?, or point me in the right direction

thanks, zac

[abhilashm86]

you need to output str instead of num1.............
check this


#include <sstream>
#include <iostream>
#include <string>

using namespace std;

int main() {
string str = "73167176";
int i = 4;
int num1;
istringstream buffer(&str[i]);
buffer >> num1;
cout << str[i] << endl;
}

[zaac]

but str is a string and i need an int

[abhilashm86]

but str is a string and i need an int

here you are reading whole string from value pointed by integer i, so read just a single character, then you'll able to print intermediate values.........

[bhagabhi]

change your line


istringstream buffer(&str[i]);


to


istringstream buffer(str.substr(4,1));

[zaac]

here you are reading whole string from value pointed by integer i, so read just a single character, then you'll able to print intermediate values.........

im trying to read a single character and convert it to an int, but when i but it into the buffer it automatically takes multiple characters.

i need it as an int so it can be used in calculations, printing it is just to test to make sure it only takes one character

zac

[zaac]

thanks bhagabhi

[MindSz]

You can also get a character and type-cast it as an int and subtract 0x30 from it. That should give you the integer value.

Here's a simple program:


#include <stdio.h>
int main(){

char c = '7';
int n = (int) c;

n -= 0x30;
printf("%d\n", n);
return 0;
}

[c0mput3r_n3rD]

You can also get a character and type-cast it as an int and subtract 0x30 from it. That should give you the integer value.

Here's a simple program:


#include <stdio.h>
int main(){

char c = '7';
int n = (int) c;

n -= 0x30;
printf("%d\n", n);
return 0;
}

+1
I find type casting to be much easier, and more readable.
You did it in c though and he's doing c++, it ends up being the same either way though.