About gcc:multiple definition of

stay ubuntu Edit in environment C Language source code

//file name main.c
#include<stdio.h>
#include "increment.c"
#include "negate.c"

int main()
{
    printf("%d\t%d\n",increment(10),negate(10));
    printf("%d\t%d\n",increment(0),negate(0));
    printf("%d\t%d\n",increment(-10),negate(-10));
    return 0;
}

//file name increment

int increment(int a)
{
    return ++a;
}

//file name negare.c

int negate(int b)
{
    return b*(-1);
}

Compile the connection through the command, and multiple definition of（ Error reporting with multiple definitions ）

modify main.c file

//file name main.c

include<stdio.h>
int increment(int a);
int negate(int b);

int main()
{
    printf("%d\t%d\n",increment(10),negate(10));
    printf("%d\t%d\n",increment(0),negate(0));
    printf("%d\t%d\n",increment(-10),negate(-10))
}

Recompile connection and execute