Referenceslides!.PDF

Reference slides You ARE responsible for the material on these slides (they’re just taken from the reading anyway). These were the slides that generated the fewest questions in years past (i.e., those you could just read and fully understand.) CS61C L04 Introduction to C (pt 2) (1) Garcia, Fall 2011 © UCB C Strings • A string in C is just an array of characters. char string[] = abc; • How do you tell how long a string is? • Last character is followed by a 0 byte (null terminator) int strlen(char s[]) { int n = 0; while (s[n] != 0) n++; return n; } CS61C L04 Introduction to C (pt 2) (2) Garcia, Fall 2011 © UCB C String Standard Functions • int strlen(char *string); • compute the length of string • int strcmp(char *str1, char *str2); • return 0 if str1 and str2 are identical (how is this different from str1 == str2?) • char *strcpy(char *dst, char *src); • copy the contents of string src to the memory at dst. The caller must ensure that dst has enough memory to hold the data to be copied. CS61C L04 Introduction to C (pt 2) (3) Garcia, Fall 2011 © UCB Administrivia • Read KR 6 by the next lecture • There is a language called D! • /d/ • Homework expectations • Readers don’t have time to fix your programs which have to run on lab machines. • Code that doesn’t compile or fails all of the autograder tests ⇒ 0 CS61C L04 Introduction to C (pt 2) (4) Garcia, Fall 2011 © UCB Pointers Allocation (1/2) • After declaring a pointer: int *ptr; ptr doesn’t actually point to anything yet (it actually points somewhere - but don’t know where!). We can