You can use affixes to help the compiler figure out the correct type of a hard coded integer. The letter L affixed to a number indicates a long integer and the letter U indicates an unsigned type:

 #define MAX 1000L  // tells the compiler to store constant as a long rather than an int#define MAX 1000U  // tells the compiler to store constant as an unsigned int 

These affixes can be used together:

 #define MAX 1000UL // unsigned long

They are also case insensitive:

 #define MAX 1000ul // also unsigned long