8.4. Formatted I / O.

I / O tasks in the C language are solved by the printf () and scanf () functions.
Output operators are used to display the values ​​of variables and text.
Texts in C are written in quotes. There is no special type for working with strings in the C language. Instead, strings are represented as an array of type char . The elements of a string, stored in an array, are written to adjacent memory cells. At the end of the line put a mark \ 0 . The presence of this mark indicates that the line must be one size larger than the number of characters. A string is declared by specifying the char type and writing the size to [] .
Example:
char name [40];
To work with strings, you must connect the string.h file to the program.
Each of the I / O functions uses a control string and a list of arguments. The control string is written first and is enclosed in quotes. Control strings and arguments are not shuffled. The control lines first of all contain an indication of the output of a value of one or another type. They are called conversion specifiers .

The main specification can be modified by inserting modifiers between the% and the conversion character.

Data entry is performed using the scanf () function. There are several input functions in the C language. scanf () is used more often than others because It has a different input format. Like the printf () function, input uses a control string followed by a list of arguments. The control string indicates which formats the input text should be converted to. As parameters, the scanf () function uses not the variables themselves, but pointers to them. To use scanf () you need to follow two rules:
1) if the function is used to read values ​​into a variable of the main type, then the name of the variable is preceded by a & .
2) if the value is read into a character array, then the & character is not put.
Conversion of a single input data is performed by specifying a conversion specifier . If more than one data is entered, they are separated by a space character.

Modifiers can be used between the% sign and the transformation symbol. If there are more than one, they should be recorded in the order indicated in the table below: