Lecture 10: Reading from files; strings

Reading from files

video

Segmentation fault video

Optional reading: 6.1

Key ideas:

• To create a file pointer, FILE *var_name
• To point it to a file, var_name = fopen("file_name", ["r" or "w"])
• Then, use fscanf and fprintf to read and write
• If a file for reading does not exist, trying to use its pointer will give a segmentation fault

Strings

Declaring and initializing strings; reading with scanf video

strcpy and strtok video

More string library functions; reading whole lines; example video

Optional reading: Chapter 8

Key ideas:

• Strings are arrays of char with a \0 at end (hello needs 6 elements to store, not 5)
• String initialization (can be done with assignment operator =)
• String assignment must be done with strcpy
• String library functions (reference: https://www.tutorialspoint.com/c_standard_library/string_h.htm)
  1. strcpy
  2. strncpy
  3. strcmpr
  4. strtok
• gets and fgets
• Converting a string to a number and vice versa