LDP-2 UNIT 4 Presentation for practical.pptx

File Management and Preprocessor
Directives in C/C++
An introduction to file handling, macros, file inclusion, and compiler control.
Presented by
• Abhay Panchal,
• Hardi Zala,
• Roshni Rajput,
• Kuldeep Makwana,
• Umang Vaghela.
Faculty: Mitisha Barot. Date: 12-04-2025.

Introduction to File Management
1 Data Storage
Enables data storage and retrieval
for later use.
2 Configuration
Stores user input, logs, or
configuration files easily.
3 Persistence
Keeps data available even after
the program terminates.

File Types in C Language
Text Files
Human-readable files, such as .txt files.
Binary Files
Machine-readable files, such as .bin files.
We'll focus on text files for simplicity.

Basic File Operations (Text Files)
#include <stdio.h>
int main() {
FILE *fptr = fopen("file.txt", "w");
fprintf(fptr, "Hello, World!");
fclose(fptr);
return 0;
}
fopen() opens a new file. w mode creates or overwrites. fprintf writes formatted data. fclose saves changes.

Reading and Writing to Files
#include <stdio.h>
int main() {
FILE *f = fopen("file.txt", "r");
char buffer[100];
fgets(buffer, 100, f);
printf("%s", buffer);
fclose(f);
return 0;
}
r mode opens an existing file for reading. fgets reads a line into the buffer.

File Inclusion
System Files
Use angle brackets, like #include
<stdio.h>.
User Files
Use double quotes, like #include
"myfile.h".
Benefits
Inclusion allows code reuse and cleaner
files.

Example
Myfile.h
#ifndef MYFILE_H
#define MYFILE_H
#define MESSAGE "Hello from
myfile.h!"
void greet();
#endif
Main.c
#include <stdio.h>
#include "myfile.h"
int main() {
greet();
return 0;
}
Myfile.c
#include <stdio.h>
#include "myfile.h"
void greet() {
printf("%sn", MESSAGE);
}

Introduction to Preprocessor Directives
Timing
Handled before the actual
compilation process.
Purpose
Help in code reusability,
configuration, and modularization.
Examples
Macros, file inclusion, and
conditional compilation.

Macro Substitution
#define PI 3.14159
#define SQUARE(x) ((x)*(x))
1 PI
PI replaces every instance with
3.14159.
2 SQUARE(x)
SQUARE(x) becomes ((x)*(x))
after preprocessing.
3 Benefits
Improves readability and reduces
code repetition.

Compiler Control Directives
#define DEBUG
#ifdef DEBUG
printf("Debug mode ONn");
#endif
Code within #ifdef runs only if DEBUG is defined.
Useful for toggling debug logs or enabling testing features.

Summary
• File management helps persist data.
• fopen, fclose, fprintf, fgets are core file functions.
• Preprocessor directives enhance flexibility and modularity:
- #define for constants/macros
- #include for modularity
- #ifdef for conditional compilation

LDP-2 UNIT 4 Presentation for practical.pptx

LDP-2 UNIT 4 Presentation for practical.pptx

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