20 cycle control

1, for the control loop

　　① for (loop variable initialization; cycling conditions; iteration loop variable) {

　　　　　　Cycle operation;

　　　 }

　　② represents a return loop condition is true (non-zero) false (0) expression

　　③for (; loop judgment condition;) and variable initialization iteration may not write (write elsewhere), but both sides can not be omitted semicolon

　　④ The initial value may be a plurality of loop initialization statement, but not the same type required, and separated by commas, variable loop iteration may be a plurality of variable iteration statement, separated by commas. Such as:

　　　　for（i=0,j=0 ; j<count ; i++, j+=2）