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Old 03-12-2006, 06:20 PM   #1
RHLinuxGUY
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If I get invalid conversion from `const char*' to `char' what should I be lookin for?


When I 'make' my program I get this error. It works just fine when all the file are combined into one file, but it got cluttered so I divided them up. Now when I do make I get this error...

george@George:~/George Lair/030506$ make
g++ -c main.cpp
main.cpp: In function `int move_left(int, int)':
main.cpp:14: error: `x' undeclared (first use this function)
main.cpp:14: error: (Each undeclared identifier is reported only once for each
function it appears in.)
main.cpp:15: error: `y' undeclared (first use this function)
main.cpp:15: error: invalid conversion from `const char*' to `char'
main.cpp: In function `int move_right(int, int)':
main.cpp:21: error: invalid conversion from `const char*' to `char'
main.cpp: In function `int move_up(int, int)':
main.cpp:27: error: invalid conversion from `const char*' to `char'
main.cpp: In function `int move_down(int, int)':
main.cpp:33: error: invalid conversion from `const char*' to `char'
main.cpp: In function `int main(int, char**)':
main.cpp:48: error: invalid conversion from `const char*' to `char'
make: *** [main.o] Error 1
george@George:~/George Lair/030506$

I'll lose the fun if I get a direct answer, but it won't be fun when I vaguely know where to begin. I know that a * is a pointer, but what is const? What do you think I should be looking for? If my question sounds to direct, then give me something that is not as direct. Thank you in advance!

--UPDATE--

I just figured out that a const char* is a char that is unmodifiable. Meaning it cannot be to the left of the = operator. So I can have a variable EQUAL the constant char, but the constant char cannot be changed. So anyways, I'll reply back once I figure out how this effects my program.

If you want the source ask me and I'll send it up the entire contents to my FTP server.

Last edited by RHLinuxGUY; 03-12-2006 at 06:24 PM.
 
Old 03-12-2006, 06:29 PM   #2
paulsm4
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Quote:
invalid conversion from `const char*' to `char'
:
You need to cut/paste at least one of lines 21, 27, 33 and/or 48. Along with the declaration of the char[] variable in question.

Quote:
x/y undeclared
:
It sounds like you're missing an "int x, y;" in your move_XXX function(s).

Here's one example of "char[]" usage that could cause such a message:

Code:
char * foo (const char * s);
...
  char mystring[] = "hello world";
  foo (s[0]);
 
Old 03-12-2006, 06:37 PM   #3
RHLinuxGUY
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O I copied and pasted over an old error message, I have got the x and y error fixed. Easy. And I think I got the const char problem fixed. Here is what I did, but if there is a mistake in my so-called fix/patch let me know.

I'm going try to keep this as clutterless and easy to read so people won't go over the edge while reading...

// I could not find a const char*, but I did find this... (In my file gSDL.cpp)
void display_bmp(char *file_name, int x2, int y2)

// Notice that char *file_name is a pointer, but not a const char. At least I
// don't think so.

... So now I added it to the my headerfiles.h

int x, y;
void fightque();
int fight();
int fightstart(int, int, int);
void display_bmp(char*, int, int);

... It seems to solve my problem, except it brings up a host of new problems. But the good part is that none of them are found in main.cpp, but instead are found in main.o.

Here is my 'make' output...

george@George:~/George Lair/030506$ make
g++ -c main.cpp
g++ -c fight.cpp
g++ main.o fight.o -Wall `sdl-config --cflags --libs` -lSDL -o test2
fight.o(.bss+0x0): multiple definition of `screen'
main.o(.bss+0x0): first defined here
fight.o(.bss+0x4): multiple definition of `x'
main.o(.bss+0x4): first defined here
fight.o(.bss+0x8): multiple definition of `y'
main.o(.bss+0x8): first defined here
main.o(.text+0x2b): In function `move_left(int, int)':
: undefined reference to `display_bmp(char*, int, int)'
main.o(.text+0x5d): In function `move_right(int, int)':
: undefined reference to `display_bmp(char*, int, int)'
main.o(.text+0x8f): In function `move_up(int, int)':
: undefined reference to `display_bmp(char*, int, int)'
main.o(.text+0xc1): In function `move_down(int, int)':
: undefined reference to `display_bmp(char*, int, int)'
main.o(.text+0x12b): In function `main':
: undefined reference to `display_bmp(char*, int, int)'
collect2: ld returned 1 exit status
make: *** [test031206] Error 1
george@George:~/George Lair/030506$

--UPDATE--

I think I found the source of my problem. I did not include gSDL.cpp... I hate not finding problems before I post it on these forums. I'll have to add them in now.

Last edited by RHLinuxGUY; 03-12-2006 at 06:39 PM.
 
Old 03-12-2006, 06:44 PM   #4
RHLinuxGUY
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Ok heres is another update. I fixed everything except multiple definitions of x and y...

Here is my make output...

george@George:~/George Lair/030506$ make
g++ -c gSDL.cpp
g++ main.o fight.o gSDL.o -Wall `sdl-config --cflags --libs` -lSDL -o test031206fight.o(.bss+0x0): multiple definition of `screen'
main.o(.bss+0x0): first defined here
fight.o(.bss+0x4): multiple definition of `x'
main.o(.bss+0x4): first defined here
fight.o(.bss+0x8): multiple definition of `y'
main.o(.bss+0x8): first defined here
gSDL.o(.bss+0x0): multiple definition of `screen'
main.o(.bss+0x0): first defined here
gSDL.o(.bss+0x4): multiple definition of `x'
main.o(.bss+0x4): first defined here
gSDL.o(.bss+0x8): multiple definition of `y'
main.o(.bss+0x8): first defined here
collect2: ld returned 1 exit status
make: *** [test031206] Error 1
george@George:~/George Lair/030506$
 
Old 03-12-2006, 07:43 PM   #5
paulsm4
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Hi -

Glad you're squared away with the initial problems (apparently you were updating your first post simultaneous with me responding); it sounds like you'll have no difficulty fixing the "multiply defined" error, too.

STRONG SUGGESTION:
Please don't use anonymous variables in your function prototypes. If you've got a parameter, please always give it a name:
Code:
POOR:
int fightstart(int, int, int);
Code:
BETTER:
int fightstart(int x, int y, int strength_level);
IMHO
 
Old 03-12-2006, 10:35 PM   #6
RHLinuxGUY
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Posts: 889
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Thank you very much. I do not remember who I got the anonymous habbit from, but I will not use your suggestion for now on. Once I get back from my friends house(correcting problems with their computers and software), I will give it a go on the solution you recommended me. Thank you again, I'll reply back as soon as humanly possible.
 
  


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