Function in c with no parameter and not returning any value ?

Example:void world1(); //function declarationvoid world2(); //function declarationchar c='*';int i,j;void main(){char *msg="I KNOWN FUNCTION";clrscr();world1(); //function callprintf("%c%22s%7c",c,msg,c);world2(); //function callgetch();}void world1() //function definition{int a=-1;for(i=0;i<15;i++){a++;for(j=0;j<30;j++){if(j>=(15-a) && j<(15+a)){printf(" ");}else{printf("%c",c);}}