Redefinition of main

Question

I started writing code in C, and I needed the toupper function in my code, so I added to ctype.h header file to include it.

All of a sudden I can't run my program because I keep getting a redefinition of main error from my compiler.

Before I added the header ctype.h, and even if I get rid of the header file ctype.h, the program runs. What do I do to fix this?

#include <stdio.h>
#include <ctype.h>

#define NAMESPACE 20

int main (void)
{  

    char first_name[NAMESPACE], middle_name[NAMESPACE], last_name[NAMESPACE];
    printf ("Please enter your first, middle and last name.\n");
    scanf ("%s", first_name);
    scanf("%s", middle_name);
    scanf ("%s", last_name);
    printf ("%s %0.1s %s", first_name, middle_name, last_name);
    return 0;
}

---

[error] redefinition of "int main()":

Here is the code saved as a header file called ctype.h in my DEV c++ ,

#include<stdio.h>
#include<conio.h>
int main (void)
{
char ch[]="I AM AN IDIOT.";
char c='A';
int i=0;
while(c)
{
c=getch();
printf("%c\a",ch[i]);
i++;
if(i==14)
{
printf(" "); i=0;
}
}
}

Answer 1

The code you posted does not explain the error message you presented. It has some issues, but none that should elicit any error. There are several possible reasons for the error, among them:

1. My best guess would be that you have another source file in the project that has its own main() function, and the IDE is configured to include both in the same target program. That might result simply by virtue of them being collocated in the same directory. That other source file might even be something dumb, such as a backup copy of the file you presented.
2. Alternatively, it may be that you have a project-local header named ctype.h, which defines a main() function, and Dev C++ is choosing that one instead of the standard library's header. (Yes, this is really just a variant on (1); there's not much leeway in "redefinition of 'int main()'".)
3. Or perhaps Dev C++ misspoke, and it's complaining about a redeclaration of main() rather than a redefinition. If its ctype.h header contained a conflicting declaration, such as int main(int argc, char *argv[]), then it might issue a complaint. In that unlikely case, you might be able to resolve the error by changing the declaration of your main() to the two-argument form.