Input/Output in C: Streams, Formatted Output with printf, and Formatted Input with scanf, Slides of Computer Engineering and Programming

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I/O in C

Lecture 6

Input/Output in C

• C has no built-in statements for input or output.
• A library of functions is supplied to perform these operations. The I/O library functions are listed the “header” file <stdio.h>.
• You do not need to memorize them, just be familiar with them.

Types of Streams in C

• Standard input stream is called "stdin" and is normally connected to the keyboard
• Standard output stream is called "stdout" and is normally connected to the display screen.
• Standard error stream is called "stderr" and is also normally connected to the screen.

Formatted Output with printf

printf ( ) ;

• This function provides for formatted output to the screen. The syntax is: printf ( “format”, var1, var2, … ) ;
• The “format” includes a listing of the data types of the variables to be output and, optionally, some text and control character(s).
• Example: float a ; int b ; scanf ( “%f%d”, &a, &b ) ; printf ( “You entered %f and %d \n”, a, b ) ;

Input/Output in C

scanf ( ) ;

• This function provides for formatted input from the keyboard. The syntax is: scanf ( “format” , &var1, &var2, …) ;
• The “format” is a listing of the data types of the variables to be input and the & in front of each variable name tells the system WHERE to store the value that is input. It provides the address for the variable.
• Example: float a; int b; scanf (“%f%d”, &a, &b);

Input/Output in C

getchar ( ) ;

• This function provides for getting exactly one character from the keyboard.
• Example:

char ch; ch = getchar ( ) ;

Input/Output in C

getc ( *file ) ;

• This function is similar to getchar( ) except the input can be from the keyboard or a file.
• Example:

char ch; ch = getc (stdin) ; /* input from keyboard / ch = getc (fileptr) ; / input from a file */

Input/Output in C

putc ( char, *file ) ;

• This function is similar to putchar ( ) except the output can be to the screen or a file.
• Example:

char ch; ch = getc (stdin) ; /* input from keyboard / putc (ch, stdout) ; / output to the Docsity.com