C stdio.h Library

C Tutorial

C stdio.h Library

In C stdio.h Library stands for Standard Input/Output in C. It provides functions for input, output, file handling, and formatting. Most C programs rely on it.

📌 Common stdio.h Functions

1️⃣ Input Functions

FunctionDescription
scanf()Reads formatted input from the console
getchar()Reads a single character from the console
gets()Reads a string from the console (unsafe, avoid in modern C)
fgets()Reads a string from a file or stdin (safe alternative)

Example:


 

2️⃣ Output Functions

FunctionDescription
printf()Prints formatted output to the console
putchar()Prints a single character
puts()Prints a string with newline

Example:


 

3️⃣ File Handling Functions

FunctionDescription
fopen()Opens a file in a specific mode (r, w, a, etc.)
fclose()Closes a file
fprintf()Writes formatted output to a file
fscanf()Reads formatted input from a file
fgetc()Reads a single character from a file
fputc()Writes a single character to a file
fgets()Reads a string from a file
fputs()Writes a string to a file
feof()Checks end-of-file
fflush()Flushes output buffer

Example: Writing to a File


 

Example: Reading from a File


 

4️⃣ Other Useful Functions

FunctionPurpose
remove()Deletes a file
rename()Renames a file
rewind()Moves file pointer to beginning
ftell()Returns current position of file pointer
fseek()Moves file pointer to specified location

Example: Using fseek() and ftell()

📌 Summary Table

CategoryFunctions
Console Inputscanf, getchar, fgets
Console Outputprintf, putchar, puts
File Handlingfopen, fclose, fprintf, fscanf, fgetc, fputc, fgets, fputs, feof, fflush
File Utilitiesremove, rename, rewind, ftell, fseek

✅ Notes

  1. Always check if file opened successfully.

  2. Prefer fgets() over gets() for safety.

  3. printf and scanf use format specifiers (%d, %f, %c, %s).

  4. fflush(stdin) is non-standard, avoid it; better use getchar() to clear input buffer.

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