NULL-valued pointer

NULL is usually represented as zero for a C pointer. However zero does not always represent NULL. Use the keyword NULL in your code to initialize pointers, as the following line shows:

MI_ROW *row = NULL;

In addition, the uses the NULL-value pointer for the following:

• To signify a default value for arguments in many functions
• To indicate an unsuccessful execution of a function that, when successful, returns a pointer to some value