Reading and Writing Files in C Programming
Reading and Writing Files in C Programming
Introduction to Reading and Writing Files in C Programming
Reading and writing files in C programming are core operations used to handle data stored in files. These operations allow programs to store, retrieve, and update data efficiently.
Reading and writing files in C programming are essential for real-world applications like databases, logs, and reports.
File Modes for Reading and Writing
Different modes are used while opening files:
Common File Modes
"r"→ Read file"w"→ Write file (creates/overwrites)"a"→ Append data"r+"→ Read and write
Writing to File in C Programming
Writing means storing data into a file.
Example: Writing Data Using fprintf()
int main() {
FILE *fp;
fp = fopen(“data.txt”, “w”);
if(fp == NULL) {
printf(“File not opened”);
return 1;
}
fprintf(fp, “Hello, this is file writing in C”);
fclose(fp);
return 0;
}
Writing Using fputc()
int main() {
FILE *fp = fopen(“data.txt”, “w”);
fputc(‘A’, fp);
fputc(‘B’, fp);
fputc(‘C’, fp);
fclose(fp);
return 0;
}
Reading from File in C Programming
Reading means retrieving data from a file.
Example: Reading Using fgetc()
int main() {
FILE *fp;
char ch;
fp = fopen(“data.txt”, “r”);
if(fp == NULL) {
printf(“File not found”);
return 1;
}
while((ch = fgetc(fp)) != EOF) {
printf(“%c”, ch);
}
fclose(fp);
return 0;
}
Reading Using fscanf()
int main() {
FILE *fp;
char str[50];
fp = fopen(“data.txt”, “r”);
fscanf(fp, “%s”, str);
printf(“Data: %s”, str);
fclose(fp);
return 0;
}
Reading Using fgets()
int main() {
FILE *fp;
char str[100];
fp = fopen(“data.txt”, “r”);
fgets(str, sizeof(str), fp);
printf(“%s”, str);
fclose(fp);
return 0;
}
Combined Example: Read and Write
int main() {
FILE *fp;
char str[50];
fp = fopen(“data.txt”, “w”);
fprintf(fp, “C Programming File Example”);
fclose(fp);
fp = fopen(“data.txt”, “r”);
fgets(str, sizeof(str), fp);
printf(“%s”, str);
fclose(fp);
return 0;
}
Important File Functions for Reading and Writing
Key Functions
fprintf()→ Write formatted datafscanf()→ Read formatted datafgetc()→ Read single characterfputc()→ Write single characterfgets()→ Read stringfputs()→ Write string
Best Practices for File Handling
Tips
- Always check if file is opened successfully
- Close file after use
- Use correct file mode
- Handle errors properly
Start Learning C Programming
Practice reading and writing files to build real-world C programming projects.
Summary
Reading and writing files in C programming are essential operations for handling data. Functions like fprintf, fscanf, fgetc, and fgets are commonly used.
FAQs
What is reading file in C programming?
It means retrieving data from a file.
What is writing file in C programming?
It means storing data into a file.
Which function is used to read character?
fgetc()
Which function is used to write string?
fputs()