c programming language macros , postfix and prefix increment, results in windows dos and codeblocks

 #include <stdio.h>
 #include <stdlib.h>

 #define comp(a,b) ((a)*(a)+(b)*(b))

 void main(void){
     int x=1;
     int y=2;
     int z=comp(x++,++y);
     printf("x = %d \ny= %d\nz= %d\n",x,y,z);
     system("pause");
 } 

output on windows dos .. when use notepad and gcc compilor directly x=3 ,y=4,z=17 output with same code compiled on codeblocks is x=3 ,y=4,z=18 please help me .. i want to know steps code will do .. i am beginner .