C++ Basit Hesap Makinesi

#include<stdio.h> 
int toplama(s1,s2); 
int cikarma(s1,s2); 
int bolme (s1,s2); 
int carpma (s1,s2); 
main() 
{ 
int s1,s2,st; 
char i; 
printf("HESAP MAKINASI S.1.0\n"); 
printf("Islemi yaziniz:\n"); 
scanf("%d%c%d",&s1,&i,&s2); 
switch(i) 
{ 
case '+':toplama(s1,s2); 
break; 
case '-':cikarma(s1,s2); 
break; 
case '/':bolme(s1,s2); 
break; 
case '*':carpma(s1,s2); 
break; 
default :printf("Yanlis islem\n"); 
} 
system ("PAUSE"); 
return 0; 
} 

toplama(s1,s2) 
{ 
         printf("Toplama isleminin sonucu:%d\n",s1+s2); 
} 

cikarma(s1,s2) 
{ 
         printf("Cikarma isleminin sonucu:%d\n",s1-s2); 
} 
bolme(s1,s2) 
{ 
       printf("Bolme isleminin sonucu:%d\n",s1/s2); 
} 
carpma(s1,s2) 
{ 
        printf("Carpma isleminin sonucu:%d\n",s1*s2); 
}