#include <string>
#include <iostream>
using namespace std;
int main()
{
char c1 = '3';
char c2 = '4';
cout << atoi(&c2);
return 0;
}
Strange problem when converting char to int
Author
I suggest using a stringstream for conversion
#include <sstream>#include <iostream>using namespace std;int main(){ int i1, i2; stringstream ss; // Feed stream with two char items separated by space ss << '3' << ' ' << '4'; cout << "The stream: " << ss.str() << endl; if(!(ss >> i1 >> i2)) // extract and convert two items from stream cerr << "Unable to convert..." << endl; cout << "The ints: " << i1 << ' ' << i2 << endl;}
Author
But why is the way i'm doing it giving such a weird result?
if i just do it for one char, it works fine
but when i do it for two chars like in the above example, it gives this weirdness..
i'm simply trying to make a menu where the user enters a single digit to specify his/her option and then it converts it to an int. i've never heard of that task requiring anything special. in fact i've never had this issue before.
if i just do it for one char, it works fine
but when i do it for two chars like in the above example, it gives this weirdness..
i'm simply trying to make a menu where the user enters a single digit to specify his/her option and then it converts it to an int. i've never heard of that task requiring anything special. in fact i've never had this issue before.
This might clearify:
The expression &c2 is not good enough.
atoi expect a char array, not the memory address of a single char.
[Edited by - pulpfist on May 11, 2007 10:12:03 PM]
char c1 = '3';char c2 = '4';// The numbers (0-9) starts at index 48 in the ascii table...cout << (int)c1-48 << ' ' << (int)c2-48 << endl;The expression &c2 is not good enough.
atoi expect a char array, not the memory address of a single char.
[Edited by - pulpfist on May 11, 2007 10:12:03 PM]
What you're doing is wrong. atoi expects a char*, but it supposes it points to a null-terminated string, not a single character. So it keeps reading past the address &c2 until it founds a 0. The result you get is entirely coincidental, it could be any other garbage value or even result in crashing the program. Your best bet is to use std::stringstream pulpfist suggested or boost::lexical_cast. If you don't use boost, I suggest you download it because it's really useful.
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