446,193 Members | 843 Online
Need help? Post your question and get tips & solutions from a community of 446,193 IT Pros & Developers. It's quick & easy.

# Help: datatypes...

 P: n/a I am writing a program where I have a subroutine which adds up a number, basically something like this; int myNumber; void add(int i){ myNumber=myNumber+i; } So everytime "add" is called myNumber increases. My problem is that myNumber is "reset" or is definet as "infinity", even though the number is not too large for the datatype used. I have tried with a couple of different datatypes. First I defined all my numbers as "double" since I don't only add integers. But when myNumber is about 6000 it is suddenly set to #INF the next time it increases. I have also tried to define the numbers as pure integers ("long"), but now the number is reset to 0 a little after it passes 600,000. Both the 'double' and the 'long' datatypes should be able to handle larger numbers than this. I am using Microsoft Developer Studio 97, on a Pentium 4 PC. Can somebody tell me what my problem is and what I should do to be able to add up more numbers? Thanks... Nov 4 '06 #1
5 Replies

 P: n/a Dala Dahlgren wrote: I am writing a program where I have a subroutine which adds up a number, basically something like this; int myNumber; void add(int i){ myNumber=myNumber+i; } So everytime "add" is called myNumber increases. My problem is that myNumber is "reset" or is definet as "infinity", even though the number is not too large for the datatype used. I have tried with a couple of different datatypes. First I defined all my numbers as "double" since I don't only add integers. But when myNumber is about 6000 it is suddenly set to #INF the next time it increases. I have also tried to define the numbers as pure integers ("long"), but now the number is reset to 0 a little after it passes 600,000. Both the 'double' and the 'long' datatypes should be able to handle larger numbers than this. I am using Microsoft Developer Studio 97, on a Pentium 4 PC. Can somebody tell me what my problem is and what I should do to be able to add up more numbers? Only if you post a small compilable example that demonstrates your problem. Otherwise all people can do is guess. Building the example code may show you the cause. -- Ian Collins. Nov 4 '06 #2

 P: n/a Dala Dahlgren wrote: I am writing a program where I have a subroutine which adds up a number, basically something like this; int myNumber; void add(int i){ myNumber=myNumber+i; } So everytime "add" is called myNumber increases. My problem is that myNumber is "reset" or is definet as "infinity", even though the number is not too large for the datatype used. I'm not getting the same behaviour. Can you maybe show how you are calling the function. We can only guess at what value is passed to the function. Are you sure you aren't invoking a factorial? Also, is myNumber initialized before use. See below. I have tried with a couple of different datatypes. First I defined all my numbers as "double" since I don't only add integers. But when myNumber is about 6000 it is suddenly set to #INF the next time it increases. I have also tried to define the numbers as pure integers ("long"), but now the number is reset to 0 a little after it passes 600,000. Both the 'double' and the 'long' datatypes should be able to handle larger numbers than this. I am using Microsoft Developer Studio 97, on a Pentium 4 PC. Can somebody tell me what my problem is and what I should do to be able to add up more numbers? Thanks... /*main.cpp*/ #include #include int myNumber(0); void add(int i) { myNumber += i; } int main() { // study numeric limits std::cout << "max integer = " << std::numeric_limits< int >::max() << std::endl; std::cout << "max long = " << std::numeric_limits< long >::max() << std::endl; std::cout << "max double = " << std::numeric_limits< double >::max() << std::endl; for(int i = 0; i < std::numeric_limits< int >::max(); ++i) { add(1); // this will take a while } std::cout << "myNumber = " << myNumber << std::endl; return 0; } /* max integer = 2147483647 max long = 9223372036854775807 max double = 1.79769e+308 myNumber = 2147483647 // <- result concurs with an integer's limits */ Nov 4 '06 #3

 P: n/a Salt_Peter wrote in message ... >/*main.cpp*/#include #include int myNumber(0);void add(int i){ myNumber += i;}int main(){ // study numeric limits std::cout << "max integer = " << std::numeric_limits< int >::max()<< std::endl; std::cout << "max long = " << std::numeric_limits< long >::max() < Different compiler? Try it. Or, am I just missing something? Obviously ms-window\$ was not involved to get us to the moon! -- Bob R POVrookie Nov 4 '06 #4

 P: n/a BobR wrote: Salt_Peter wrote in message ... /*main.cpp*/ #include #include int myNumber(0); void add(int i){ myNumber += i;} int main(){ // study numeric limits std::cout << "max integer = " << std::numeric_limits< int >::max() << std::endl; std::cout << "max long = " << std::numeric_limits< long >::max() << std::endl; std::cout << "max double = " << std::numeric_limits< double >::max() << std::endl; for(int i = 0; i < std::numeric_limits< int >::max(); ++i){ add(1); // this will take a while } std::cout << "myNumber = " << myNumber << std::endl; return 0; } /* max integer = 2147483647 max long = 9223372036854775807 max double = 1.79769e+308 myNumber = 2147483647 // <- result concurs with an integer's limits */ Ever try to 'print' that double max() on windows, in 'fixed' format? [ this is on win98, MinGW(GCC 3.3.1 ] // int main(){ std::string DblMax(""); { std::ostringstream out; out.precision( 400 ); out.setf( std::ios_base::fixed ); // cout<<"out.precision()="<::max(); // GNU/Linux OK // - biggest I could get to 'print' - double tmp( std::numeric_limits::max() / 1.0e+276); // max() / 1.0e+275==boom out<<(tmp); DblMax=out.str(); } std::cout <<"DblMax=out.str() = "< Different compiler? Try it. Or, am I just missing something? Obviously ms-window\$ was not involved to get us to the moon! -- Bob R POVrookie lol Sorry, no windows here. linux FC5, gcc 4.1.1 x86_64, FX dual-core. Which explains the output above. And yes, it prints the whole thing. And i do mean the *whole* thing. If you don't mind, i'll spare the newsgroup. Nov 4 '06 #5

 P: n/a Dala Dahlgren First I defined all my numbers as "double" since I don't only add integers.But when myNumber is about 6000 it is suddenly set to #INF the next time itincreases.I have also tried to define the numbers as pure integers ("long"), but nowthe number is reset to 0 a little after it passes 600,000.Both the 'double' and the 'long' datatypes should be able to handle largernumbers than this. Have you tried "long long"? I've seen systems where "long" is no longer than "int", but "long long" is twice as long. I think this is for historical reasons. Steve Nov 5 '06 #6

### This discussion thread is closed

Replies have been disabled for this discussion.