hi I want to use a very larger integer variable to store a value , an unsigned long integer ( 4 bytes unsigned long integer)maybe overflow! how can i deal with this situation?
You'll just have to write your own functions (or macros) to perform whatever functions you require.
You could kept your larger number in a char array, then, write your own funtion to do add, sub, etc. e.g. char Num1[]="5555555"; char Num2[]="99999999999999" char *Num3; Num3=MyAdd(Num1,Num2);