From: "pcgamesmaster AT hotmail DOT com" <pcgamesmaster AT hotmail DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: funny for and while loop and c++ problems
Date: Fri, 05 Feb 1999 01:17:58 +0800
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

question 1:

what is the difference between the first and second snippet of code?
why doesn't the first one work in djgpp?

========================================================================
    lp = 0;
    while (!key[KEY_ENTER]) {
        while (lp < 256) {
            if (pal[lp].r > 0) {
                pal[lp].r--;
            }
            if (pal[lp].g > 0) {
                pal[lp].g--;
            }
            if (pal[lp].b > 0) {
                pal[lp].b--;
            }
            lp += 1;
        }
        set_palette(pal);
    }
========================================================================
    while (!key[KEY_ENTER]) {
        for (lp = 0; lp < 256; lp++) {
            if (pal[lp].r > 0) {
                pal[lp].r--;
            }
            if (pal[lp].g > 0) {
                pal[lp].g--;
            }
            if (pal[lp].b > 0) {
                pal[lp].b--;
            }
        }
        set_palette(pal);
    }
========================================================================

i think the problem with the first one is that it doesn't execute the
innermost while loop. why? this is part of a program using the allegro
graphics library to fade a display to black. however, the display using
the first snippet of code doesn't work, while the second does ...




question 2:

while i attempt to compile c++ code in djgpp using the command-line

gcc <filename.cpp>

djgpp returns me with

========================================================================
c:/djgpp/tmp\ccdaaaaa(.text+0x1a):testcpp.cc: undefined reference to
`endl(ostream &)'
c:/djgpp/tmp\ccdaaaaa(.text+0x24):testcpp.cc: undefined reference to
`cout'
c:/djgpp/tmp\ccdaaaaa(.text+0x29):testcpp.cc: undefined reference to
`ostream::operator<<(char const *)'
c:/djgpp/tmp\ccdaaaaa(.text+0x34):testcpp.cc: undefined reference to
`ostream::operator<<(ostream &(*)(ostream &))'
========================================================================

this is the program listing :

========================================================================
#include <iostream.h>

main() {
    cout << "Hello World!" << endl;
}
========================================================================

how do i compile c++ code in djgpp?


thanks in advance for any help given ...

lee.