C Programming Input and Output Functions: Formatted vs. Unformatted

Introduction

In the world of programming, efficient input and output handling is crucial. This blog post explores the different input and output functions available in the C programming language, categorizing them as formatted and unformatted, and discusses their special features and use cases.

Formatted Input Functions:

Function	Description	Syntax
scanf	Reads formatted input from standard input, allows specifying format specifiers for input data.	int scanf(const char *format, ...);
fscanf	Reads formatted input from a file stream, supports format specifiers for data parsing.	int fscanf(FILE *stream, const char *format, ...);
sscanf	Reads formatted input from a string, similar to scanf, but operates on strings.	int sscanf(const char *str, const char *format, ...);
scanf_s	A safer version of scanf introduced in C11, which includes buffer size specification to prevent buffer overflows.	int scanf_s(const char *format, ...);
fscanf_s	A safer version of fscanf introduced in C11, with buffer size specification for file input.	int fscanf_s(FILE *stream, const char *format, ...);

Unformatted Input Functions:

Function	Description	Syntax
getchar	Reads a single character from standard input, useful for raw character input.	int getchar(void);
getch	Reads a single character from standard input without echoing to the screen, often used for input masking.	int getch(void);
getche	Similar to getch, but echoes the character back to the screen, suitable for password input.	int getche(void);
gets	Deprecated in C11 due to security concerns, reads a line of text from standard input.	char *gets(char *str);
fgets	Reads a line of text from standard input or a file stream, with buffer size specification for safety.	char *fgets(char *str, int size, FILE *stream);
getw	Reads a binary integer from a file stream.	int getw(FILE *stream);
getwc	Reads a wide character from standard input or a file stream.	wint_t getwc(FILE *stream);

Formatted Output Functions:

Function	Description	Syntax
printf	Outputs formatted data to standard output, uses format specifiers for display.	int printf(const char *format, ...);
fprintf	Outputs formatted data to a file stream, supports format specifiers for file output.	int fprintf(FILE *stream, const char *format, ...);
sprintf	Outputs formatted data to a string, similar to printf, but stores the result in a string.	int sprintf(char *str, const char *format, ...);
printf_s	A safer version of printf introduced in C11, includes buffer size specification to prevent buffer overflows.	int printf_s(const char *format, ...);
fprintf_s	A safer version of fprintf introduced in C11, with buffer size specification for file output.	int fprintf_s(FILE *stream, const char *format, ...);

Unformatted Output Functions:

Function	Description	Syntax
putchar	Writes a single character to standard output.	int putchar(int c);
putch	Writes a single character to standard output without newline, often used for inline character output.	int putch(int c);
putc	Writes a character to a file stream.	int putc(int character, FILE *stream);
puts	Writes a string with a newline to standard output.	int puts(const char *str);
fputc	Writes a character to a file stream.	int fputc(int character, FILE *stream);
fputs	Writes a string to a file stream.	int fputs(const char *str, FILE *stream);
putw	Writes a binary integer to a file stream.	int putw(int w, FILE *stream);
putwc	Writes a wide character to a file stream.	wint_t putwc(wchar_t wc, FILE *stream);

Conclusion

Understanding input and output functions in C is essential for building robust programs. Whether you need controlled, formatted input or flexible unformatted input, C provides a range of functions to suit your needs. Similarly, for output, you can format and display data as required.