The PrintF function is called a format output function, and the last letter f is the meaning of "format). Its function is to display the specified data on the display screen by the format specified by the user.
General form of Printf function call
The Printf function is a standard library function, its function prototype in the header file "stdio.h". However, as a special case, the stdio.h file must be included before using the Printf function. The general form of the PrintF function call is:
Printf ("Format Control String", Output Table Layer)
Be
The format control string is used to specify the output format. Format control strings can be composed of two format strings and non-format strings. The format string is a string that starts with%, with a variety of format characters in%, to illustrate the type, form, length, and lower number of output data. like:
"% D" means it is output according to the decimal output;
"% Ld" means output according to the decimal output;
"% C" indicates that the output is output, etc.
Non-format string slave output, prompts in display. Each output item is given in the output list, requiring the format string and each output item to correspond to the number and type.
Format string
1) Type
Type characters to indicate the type of output data, its formatting characters and me functions as shown in the following table: Format Characters
D outputs a symbol integer (positive number does not output symbol)
O Output unsigned integers in octal form (no output prefix 0)
X, x output unsigned integers in hexadecimal form (no output prefix ox)
U Output unsigned integers in decimal form
F In decimal form, double accuracy
E, E output a single, double precision implement in the index form
G, g with a shorter output width output single, double precision real number in% f or% e
C Output a single character
S output string
2) Sign
The logo character is -, +, # and space four, its meaning shown in the table: flag meaning
- Results left aligned, right edges
+ Output symbol (positive or negative)
The space output value is positive and the crown is spaced, and the crown is negative.
# 有 有 有 类, 类;
For the O class, prefix O;
For the X class, add 0x when output;
The decimal point is given when e, g, and fang is decimal.
3) Output minimum width
Use a decimal integer to indicate the minimum number of outputs. If the actual number of digits is more than the defined width, then the actual number of digits is output, and if the actual number of digits is less than the defined width, the space or 0 is supplied.
4) accuracy
The accuracy format begins with ".", Followed by the decimal integer. The meaning of this is: If the number is output, the number of digits is indicated; if the output is the character, the number of output characters is indicated; if the actual number of digits is greater than the defined accuracy, the exceeding portion is cut.
5) length
The length format is H, L, H indicates that the shorter amount output is output, and L is indicated by the long output.
#Include "stdio.h"
#Include "string.h"
Int main ()
{
CHAR C, S [20];
INT A = 1234;
Float f = 3.141592653589;
Double x = 0.12345678912345678;
STRCPY (S, "Hello, World");
C = '\ x41';
Printf ("a =% D \ n", a); // output according to the decimal integer format, display a = 1234
Printf ("A =% D %% \ n", a); // output% number result A = 1234%
Printf ("a =% 6d \ n", a); // output 6-digit decimal integer left filling, display a = 1234
Printf ("a =% 06d \ n", a); // output 6-digit decimal integer left to supplement 0, display a = 001234
Printf ("a =% 2D \ n", a); // a more than 2 digits, press actual output a = 1234
Printf ("a =% - 6d \ n", a); /// output 6-digit 10-input integer to the right side, display a = 1234
Printf ("f =% f \ n", f); // floating point effective number is 7 bits, result f = 3.141593
Printf ("f = 6.4f \ n", f); // output 6 columns, 4 digits after decimal point, result f = 3.1416
Printf ("x =% lf \ n", x); // output long floating point number x = 0.123457
Printf ("x =% 18.16LF \ n", x); // output 18 columns, 16 digits after decimal point, x = 0.1234567891234567
Printf ("C =% C \ n", c); // Output Character C = a
Printf ("c =% x \ n", c); // ASCII code c = 41 with hexadecimal output characters
Printf ("s [] =% s \ n", s); // Output array string s [] = Hello, World
Printf ("s [] =% 6.9s \ n", s); // outputs up to 9 characters String s [] = Hello, Wor
Return 0;
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