1. IO revisited CSE 2451 Rong Shi

2. stdio.h Functions – printf – scanf(normally stops at whitespace) – fgets – sscanf Standard streams – stdin(defaults to keyboard) stdin – stdout(defaults to console) stdout – stderr(defaults to console) stderr

3. scanf and incorrect input scanf input is based on pattern matching If incorrect input is entered, the pattern is not matched and the input characters remain in the buffer See scanftest.c

4. fgets – get string from stream char *fgets(char *s, int size, FILE *stream); – Read in size - 1 characters from the stream and stores it into *s pointer. – The string is automatically null-terminated. – fgets stops reading in characters if it reaches an EOF or newline. Ex: char s[100]; fgets(s, sizeof(s), stdin); // read a line from stdin Use sscanf to process the string

5. sscanf – read formatted data from string int sscanf(const char *str, const char *format,...); – *str is a string / character array / pointer to character – *format is a string literal – Additional arguments are pointers to the types in *format Ex: int i; char s[100]; fgets(s, sizeof(s), stdin); // read a line from stdin sscanf (s,"%d", &i);

6. IO redirection When running an executable > redirects output < redirects input | pipe (stdout from one program to stdin of another) Examples: testprog > fileout (output of testprog goes to fileout) testprog < filein (input of testprog comes from filein) prog1 | prog2 (input of prog2 comes from output of prog1)