Limit * Pointer and Array only have one dimension * Don't support local array * When you initialize global variable or array ,don't use negative * Increment and Decrement only used for basic type variable, such as i++ i-- ++j --j * Function parameter's max quantity is 6 * Local scope only have one depth Right int main() { int a=5; long b=a+a; ... ... int i; for(i=0;i<b;i++) { ... ... } } False int main() { { int a=0; //xxx } int b=10; if(b>0) { int c=0; //xxx ... ... } for(int i=0;i<10;i++) //xxx { ... ... } while(1) { char* s="local"; //xxx ... ... } }