Trick Collection

1,arrays is automatic counting,

A second shorthand for arrays is automatic counting, in which you 

let the compiler determine the size of the array based on the 
number of initializers: 
int c[] = { 1, 2, 3, 4 }; 
Now if you decide to add another element to the array, you simply 
add another initializer. If you can set your code up so it needs to be 
changed in only one spot, you reduce the chance of errors during 
modification. But how do you determine the size of the array? The 
expression sizeof c / sizeof *c (size of the entire array divided by 
the size of the first element) does the trick in a way that doesn’t 
need to be changed if the array size changes5
: 
for(int i = 0; i < sizeof c / sizeof *c; i++) 

c[i]++; 

2,do{} while(0);