Many built-in input and output functions are provided in the C language.
Standard file definition
All devices will be processed in the C language. In order to access the keyboard and screen, the following three files open when the program is executed.
The input / output in the C language typically uses the built-in Printf () and scanf () functions.
The scanf () function is used to read and format from the standard input (keyboard), and the Printf () function sends a formatted output to the standard output (screen).
#include // Execute the Printf () function requires the library
INTMAIN ()
{Printf ("STM32"); // Displays the content RETURN0 in quotes;
}
Compile the above programs, the output results are:
STM32
Analysis:
The main () function needs to be included in the C language program. The code starts from the main () function.
Printf () is used to format the output to the screen. The Printf () function is declared in the "stdio.h" header file.
Stdio.h is a header file (standard input output header file) and # include is a pre-processing command to introduce header files. When the compiler encounters a Printf () function, if the stdio.h header file is not found, compiling errors will occur.
RETURN 0; the statement is used to represent the exit program.
% D formatted output integer
Compile the above programs, the output results are:
Number = 5
Use "% D" (integer) in quotation marks in the printf () function to match the integer variable Testinteger and output to the screen.
% F formatted output floating point data
#include
INTMAIN ()
{floatf;
Printf ("Enter a Number:");
//% F matches floating point data scanf ("% f", & f);
Printf ("Value =% f", f);
Return0;
}
GetChar () and PUTCHAR () functions
The INT PUTCHAR (INT C) function outputs the character to the screen and returns the same character. This function will only output a single character in the same time. You can use this method in a loop to output multiple characters on the screen.
The int getchar (void) function reads the next available characters from the screen and returns it to an integer. This function will only read a single character in the same time. You can use this method in a loop to read multiple characters from the screen.
Look at the following example:
The above code is compiled and executed, it will wait for you to enter some text, when you enter a text and press Enter, the program will continue and only read a single character, as follows:
$. / a.ounsenter a value: Runoobyou Entered: R
Gets () and PUTS () functions
The char * GETS (CHAR * S) function reads a row to the buffer pointed to S, until a terminator or EOF.
INT PUTS (Const Char * S) function writes string s and a trailing liner in STDOUT.
Run as follows:
$. / a.ounsenter a value: runoobyou entered: RunoB
Scanf () and Printf () functions
INT scanf (const char * format, ...) function Reads input from standard input stream stdin and browses the input according to the Format provided.
The int printf (const char * format, ...) function writes the output to the standard output stream stdout and generates an output based on the provided format.
Format can be a simple constant string, but you can specify% S,% D,% C,% F or the like to output or read strings, integers, characters, or floating point numbers, respectively. There are many other available format options that can be used as needed. For complete details, you can view the reference manual for these functions. Now let's deepen understanding through the simple instances below:
Run is shown below:
$. / a.ounsenter a value: RunoB 123you entered: RunoB 123
It is worth noting that the format of Scanf () looks forward is the same as the% s and% D you given, which means you have to provide effective input, such as "string integer, if you provide" string string "or "Integer Integer", it will be considered an incorrect input. In addition, when reading a string, as long as you encounter a space, scanf () will stop reading, so "this is test" is three strings for scanf (). , Read the full article, original title: Input & output in C language
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