Input/Output statements

Input/Output statements

• Reading data from input device and displaying the result on the screen are the two main tasks of any programming in C
• In ‘C’ language the input and output operations are carried out by using standard functions.
• The programs for these functions are kept in the file.
• The file must be included in the program to use these functions using the preprocessor directive as: #include

The i/o functions are classified into 2 types:

C supports two formatting functions: printf( ), scanf( )

• printf( ) is used to convert data stored in the program into a text stream for output to monitor
• scanf( ) is used to convert the text stream coming from the keyboard to data values and stores them in program variables
• printf( ) function stands for print formatting
• printf function takes data values, converts them to a text stream using formatting specifications in the control string and passes the resulting text stream to the standard output.

Rules

• The name of printf function should be in lower case
• The input (or arguments) to printf function are given within round or circular paranthesis
• At least one input is required and the first input to printf function should always be a string literal
• The inputs are separated by commasIf values of identifiers are to be printed with the help of print function, the first argument print function should be a format string (control string)
• Format string consists of format specifiers.
• A format specifier specifies the format according to which the format should be done

Syntax of control string

• Each control string must begin with %
•  Flags is an optional argument which specifies output justification such as numerical sign, trailing zeros or octal, decimal or hexadecimal prefixes

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