/in/ex5.c: In function 'main':
/in/ex5.c:9:19: error: 'o' undeclared (first use in this function)
     for(i=1; i <= o=integer1 && i <= integer2; ++i)
                   ^
/in/ex5.c:9:19: note: each undeclared identifier is reported only once for each function it appears in