CIS 2500 Lecture Notes - Lecture 5: Null Character, Buffer Overflow, C Dynamic Memory Allocation

• School: University of Guelph
• Department: Computing and Information Science
• Course: CIS 2500
• Professor: Deborah Stacey

Document Summary

Creating an array of strings: create an array of pointers to characters. Put the strings (arrays of characters) at the end of the pointers (this is a 2d array) Code to allocate an array of strings char **sptr; int num = 3; int i; /* declare a pointer-to-pointer variable sptr */ sptr = malloc (sizeof(char *) * num); /* allocate the memory for the char pointers */ /* for each element in the array, allocate space for the character string and point to them from the array of pointers. Copy the string name into the allocated space. for (i = 0; i < num; ++i) { sptr[i] = malloc (sizeof(char) * 5); strcpy(sptr[i], name); /* we"ve created a 3 (strings) by 4 (chars) array */ strcpy is bad though! We don"t know if we"ll have a buffer overflow! Buffer overflow is exploitable with malicious code look into it.