Standard Input And Output

Standard Input

      Anything given to the computer is called input. The input is mostly given to the computer through keyboard. Keyboard is called the standard input device. The input given to the computer through keyboard is called standard input.
      Data is given to the computer program as input for processing. Input can be given to the computer through keyboard during program execution. C-language provide various standard input library functions. These functions are used to get input from user through keyboard during execution of program. The important and commonly used standard input functions in C language are as follows:

• scanf()
• gets()
• getch()
• getche()

Standard Output

      The processed data is called output. The program gets input data, processes it and gives result as output. The output is mostly displayed on the display screen (monitor). The display screen is standard output device. The output displayed on the display screen is called standard output.
      C-language also provides various standard output library functions. These functions are used to display the output of the program on the display screen. The important and commonly used standard output functions in C language are as follows:

• printf()
• puts()

      The standard input and output functions are defined in the header file "stdio.h" (stdio stands for standard input and output). This header file must be included in the program if any standard input/output function is used in the program.