1. Introduction to C Programming
ET2560 Introduction to C Programming
Introduction to C Programming
Unit 9 Manipulating Strings
File Processing
Unit 1 Presentations

2. Unit 8 Review
Unit 9: Review of Past Material

3. Unit 8 Review Arrays Collection of adjacent memory cells
Each element has the same data type
Array declaration must include size in brackets, after name
Array size is a positive integer
To access array element, follow the name with subscript
Subscript is an integer expression (index) in square brackets
Array initializer list in braces
Parallel arrays are 2 or more related arrays with identical size
Can be passed as argument to function, but not returned

4. Strings String is not a recognized separate data type in C
String variable is an array of characters
Sized to accept the maximum number of characters
Characters start with element zero
All strings must end with a zero-value character '\0'

5. String Library Functions
Unit 9: String Manipulation and File Processing

6. String Library
Since strings are arrays, not single variables, can't use operators
Instead, the string library provides functions
strcpy(src, dest) - copy "src" (source) to "dest" (destination)
strlen(s) - returns the length of string "s" (without 0 terminator)
strcat(src, dest) - concatenate "src" to end of "dest"
strcmp(s1, s2) - compares "s1" to "s2", returns an int code
If s1 precedes s2, returns negative value
If s2 precedes s1, returns positive value
If equal, returns zero
sprintf() - puts formatted data in a string
sscanf() - gets formatted data from a string

7. Using Files in C
Unit 9: String Manipulation and File Processing

8. Files in C All file functions require a file pointer (FILE *)
The file library functions (in <stdio.h>) perform file ops
Must open a file before using it
fopen() library function - returns a file pointer
Can open for binary or text file access
Text files store data in readable characters - easy to change with editor
Binary files store data in machine format - faster to read and write
Can open for reading or writing
Reading - accesses but does not change a file, used for input
Writing - empties or creates a file, then program outputs data
When finished using a file, close it with fclose()

9. Working With Text Files
Text files treated like sequential stream of bytes
Typically processed from beginning to end
To output data to a text file
fprintf() - Like printf(), but output goes to the file
putchar() - Can output one character at a time to the file
puts() - Can output a string to the file
To input data from a text file
fscanf() - Like scanf(), but input comes from the file
getchar() - Can input one character at a time from the file
gets() - Can input a string from the file

10. Working With Binary Files
File is a sequential collection of binary data bytes
Typically processed from beginning to end
Function fwrite() used to output binary data
Must provide address of variable, number of bytes, a multiplier (useful for an array size), and file pointer
Function fread() used to input binary data