Ah ok now I understand because that's what I used to do by removing the main function it worked thanks for your help🙏🏽

When i create the command-line tool project and run it without adding file i don't get the duplicate message the code : #include stdio.h int main () {   int (a);   int (b);   int (i);   printf("Give a number");   scanf("%d",&a);   for (i=1;i=10;i++)   {     b=a*i;     printf("%d*%d=%d\n",a,i,b);   } }

When creating the xcode project I chose the command line tool and choose c file after creating it there is a first file that displays hello word but each time I create a new c file there is another one with the extension.h which I do not understand but in codand in the c file when I run it the error is displayed