Core · Module 5 · Lesson 1 of 12
File Handling with Standard I/O
Open, read, write, and close text files safely with C's buffered stdio library before moving down to POSIX file descriptors.
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By the end you can
- Open files in the correct mode and check every operation for failure
- Read text line by line into a caller-owned buffer
- Write transformed text through a buffered output stream
- Close files on every path and report errors clearly
Builds on C-Style Strings and Buffer Bounds.
01 · A question first
A file is much larger than the fixed buffer in your program. How can a C program copy and transform it without loading the entire file into memory, and what should it do when the file cannot be opened or a write fails?
Make a guess before you read on.
02 · The idea
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What's inside
- Start with the problem
- Understand the stream operations
- Build the program in milestones
- Trace the data flow
- Show the complete code
- Why this design is correct
- What it costs
- Pitfalls and variations
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