saw that Narue posted first but it still adds a bit more info
no. srand sets the seed, it doesnt generate random numbers. the seed is a number that rand uses to generate random numbers.
rand potentially generates large numbers but some maths is all you need to put some boundaries on it:
x = rand() % 10;
the % sign is modulus, it calculates the remainder from the division (divide by 10 in this case). so thinking about it, this means that x could only equal a number from 0 - 9.
good point about the pointer. good point about me completing the whole thing (I got a bit carried away :)). in my defence about the extra parameter, I was copying what they had done for their length function, and its harder to overload without the extra parameter.
[EDIT]: oh wait, not aimed at me. but the bit about overloading still stands (but then i suppose you could use copy() and copy_step2(). my advice, dont use a recursive function where a loop would suffice :))
out of interest mike. how would you differentiate between the 'base' call to copy and the iterating call to copy
OK. I tried (and failed) to keep to the same code style as the one you had. (and cleaned up with some const correctness :) ) I came up with this (included main() to show how to use)
the RecursiveCopy function with no int argument checks to see if old_str is valid and if new_str is valid. it then calls the RecursiveCopy function with the int argument and it iterates through old_str and copies the data char by char into new_str
hope you like it :)
PS: how do you feel about letting a 15 year old do your homework :) (if it is homework)
#include <windows.h>
#include <iostream>
using std::cout;
int length(const char* str, int l){
int len=0;
if(str[l]){
len = length(str,l+1);
} else {
return l;
}
return len;
}
int length(const char* str){
if(str == NULL){
return 0;
}else{
return length(str, 0);
}
}
void RecursiveCopy(const char* old_str, char* new_str, int iterator){
if(old_str[iterator]) // stops at \0
{
new_str[iterator] = old_str[iterator];
RecursiveCopy(old_str, new_str, iterator + 1);
}
else
{
new_str[iterator] = '\0'; // need to terminate the copied string
return;
}
}
// assumes new_str is allocated
bool RecursiveCopy(const char* old_str, char* new_str){
if(old_str == NULL){
cout << "Could not copy, string is empty\n";
return false;
}else if(length(new_str) < length(old_str)){
cout << "Could not copy, destination is too small to fit the origional string into\n";
return false;
}else{
RecursiveCopy(old_str, new_str, 0);
return true;
}
}
int main()
{
char* test = …
a pointer (or reference) is like a sign saying "this is where ... is". as you (should) know any variable you create is allocated in ram and given an address so the program knows where to find it.
if you point pointer to a variable then you can use the pointer as a variable its self eg you can print it with cout, point it to somewhere else but you can also access the variable through it. a reference is like a pointer but you cant treat it as a variable. you can only access the data it points to (so think of (type& x) as an alias and (type* x) as a sign showing the function where to find x)
so if you have void function(type x) { return; } and you call it like so function(AnObject); a copy is given to the function
sorry if im going a bit too in depth and ask if u don't get something. and don't forget to mark as solved :)
srand sets the seed for the random number generator (it takes the number you put in and passes it through a logarithm which generates a pseudo(fake, not totaly random) set of numbers). setting it by time(), you almost never get the same seed twice and so GREATLY improves randomness.
in debug mode maybe the copies are not deleted after the function returns and so there is no error. to test this see if the addresses of n3 and n5 match the pointers to them in n4
you were trying to delete the cptr array itsself. not the things inside it, so I added a loop to do this
array values start at 0 so I changed some loops or you would get segmentation faults trying to access the item above the one you wanted (eg 2 items you would have instead of 0 and 1, printed item 1 and 2 (and 2 would not exist!!))
maybe not necessarily, but I added memsets to make sure the string terminates (if its filled with rubbish it may think its longer than it actually is)
removed system("pause") in favour of cin.get() (does the same thing but cin.get() is less resource heavy ect..)
this now compiles ok with minGW and runs fine for me. see if it works for you.
#include<iostream>
#include<cstring>
using namespace std;
class city
{
protected:
char *name;
int len;
public:
void getname(void)
{
char *s;
s= new char[30];
memset(s, '\0', sizeof(char) * 30);
cout<<"Enter city name: ";
cin>>s;
len= strlen(s);
name= new char[len+1];
strcpy(name,s);
}
void printname()
{
cout<<name<<"\n";
}
};
int main()
{
city *cptr[10];
int n = 0;
int option;
do
{
cptr[n]= new city;
cptr[n]->getname();
n++;
cout<<"Do you want to enter one more name?\n";
cout<<"(Enter 1 for yes 0 for no):";
cin>>option;
}
while(option);
cout<<"\n";
for(int i=0; i<n; i++)
{
cptr[i]->printname();
}
for(unsigned short i = 0; i < n; ++i)
{
delete cptr[i];
}
cout<< "\npress …
I am getting the error: There is no disk in the drive. Please insert a disk into drive \Device\Harddisk1\DR1.
I have already read the answers of previous posts, but none of them fit to my situation.
I am running code blocks from a usb stick. When I start debugging I get the error. not just once, it never goes away and the debugger never starts. (I have to use task manager to close it and make the error stop popping up)
I have had the error elsewhere but I have always been able to click it away so it hasn't been a problem
here are the drives in my computer:
OS C: hard drive not hidden EXTERNAL X: external hard drive not hidden
DVD-RW D: not hidden RemovableDisks E: F: G: H: all hidden my usb stick R: not hidden
putting it outside of main() means that it isn't called when the program is run. and I think the errors happened because the function uses argc and argv which are not in the global scope (they can only be used inside main())
I am trying to move a project from CodeBlocks to visual c++. (it compiles fine using minGW) I am using the 2010 express version. when I compile the projectusing VC++ I get the errors below. I have done some research and it is comming from including windows.h. to test this I made a simple project (default console project) and included windows.h and I got the same errors.
does anyone know why they are happening?
1>------ Build started: Project: test of and operator, Configuration: Debug Win32 ------ 1> test of and operator.cpp 1>c:\program files (x86)\microsoft sdks\windows\v7.0a\include\driverspecs.h(142): error C2008: '$' : unexpected in macro definition 1>c:\program files (x86)\microsoft sdks\windows\v7.0a\include\driverspecs.h(294): error C2008: '$' : unexpected in macro definition 1>c:\program files (x86)\microsoft sdks\windows\v7.0a\include\driverspecs.h(295): warning C4005: '__' : macro redefinition 1> c:\program files (x86)\microsoft sdks\windows\v7.0a\include\driverspecs.h(142) : see previous definition of '__' 1>c:\program files (x86)\microsoft sdks\windows\v7.0a\include\driverspecs.h(308): error C2008: '$' : unexpected in macro definition 1>c:\program files (x86)\microsoft sdks\windows\v7.0a\include\driverspecs.h(309): warning C4005: '__' : macro redefinition 1> c:\program files (x86)\microsoft sdks\windows\v7.0a\include\driverspecs.h(295) : see previous definition of '__' 1>c:\program files (x86)\microsoft sdks\windows\v7.0a\include\driverspecs.h(312): error C2008: '$' : unexpected in macro definition 1>c:\program files (x86)\microsoft sdks\windows\v7.0a\include\driverspecs.h(313): warning C4005: '__' : macro redefinition 1> c:\program files (x86)\microsoft sdks\windows\v7.0a\include\driverspecs.h(309) : see previous definition of '__' 1>c:\program files (x86)\microsoft sdks\windows\v7.0a\include\driverspecs.h(316): error C2008: '$' : unexpected in macro definition 1>c:\program files (x86)\microsoft sdks\windows\v7.0a\include\driverspecs.h(317): warning C4005: '__' : macro redefinition 1> c:\program files (x86)\microsoft sdks\windows\v7.0a\include\driverspecs.h(313) : …
I know it is possible in glOrtho() but how would I make a 3D scene stretch.
for example if I rendered a cube, in the middle of a window, and then made the window longer, instead of the cube stretching, I would see more to the left and right of it, and I do not want this :(.
I have made my own image load function that reads the file extension and loads the image with the appropriate method. but at the moment it can only load bitmaps. and i know now why the image wasn't loading properly, the image was 8 bit but the function was reading it assuming it was 24 bit. how could i discard the pixels that are a certain colour (the colour around the edge)?
that's for Microsoft visual studio though, i use code blocks. I copied glut.h to include/GL/' but in lib, where it tells me to put glut32.dll, glut32.lib and glut.def the folder currently only contains .a and .o files, should I Put them there anyway?
and no, I don't have glut.h. I wouldn't use it (I make my windows with the win32 api) but its a pain when I'm trying to see how other peoples code works
well, I copied and pasted the code first to see if it worked before writing it myself and I didn't get any compiler errors, that's a start. but I don't know if it will work yet.
would there be anything wrong with making an includes.h which has all of the .h files my project needs to link to. or is it better to link to them when needed?
in openGL how can I make the left of the screen = 0 and the right to = 10 or somthing, and the top = 0 and the bottom = -10. because i dont like working with numbers only ranging from -1.0 to 1.0. i read here that the coordinate system could be whatever you wanted it to be but so far i have not found a command that changes it.
sorry you didnt make it clear what you wanted. if you want to use a graphics library then open gl and glut would be quite easy. again im not sure this is what you want but check out http://www.videotutorialsrock.com/ also maybe wxWidgets
I have been trying for ages to get glut working (in code blocks) and now it works... sort of. I can compile and run applications but it comes up with several warning: ignoring #pragma comment errors in glut.h. I got the glut.h file from here. because all other downloads of glut I used didn't work at all. why am I having this trouble with installing glut?
