Note printf scanf

(2.1) Grammar printf

Print F:format format

printf prints in format, output to console

printf: Displaying an integer

With%d (d:decimal)

Decimal English [DESML]

Adj. 10 rounded, fractional

printf ("A:%d\n,") ———— > A:33

printf ("A:%d,b:%d \ n", 32,33)

———— >a:32 b:33

Specify the number of integers:

Specify the number of digits to display, the alignment display:%3d or%4d

int a = 3;

int B = 33;

int c = 333;

printf ("Number:%d \ n", a);

printf ("Number:%d \ n", b);

printf ("Number:%d \ n", c);

printf ("Number:%03d \ n", a);

printf ("Number:%03d \ n", b);

printf ("Number:%03d \ n", c);

"03d" is used to align up and down, the width is the same

Int--integer integer variable

printf: Displaying a decimal

With%f (f = float)

printf ("x =%f \ n", 12.35);

printf ("x=%f, y=%f \ n", 12.35, 90.01)

Use double to denote decimals

Double x=123.456

Double y=99.87

printf ("X=%f,y=%f \ n", x, y)

Double: Variable type

X: Variable Name

123.456: Initial value

#include <stdio.h>

int main ()

{

int a =10

Double x=123.456; Double Float-point

printf ("x:%f\n", X);

return 0;

}

——— >x:123.456

Specify the number of digits after the decimal point

Double x =12.45678

Specifies 2 digits after the decimal point, rounded,

Using%.2f

printf ("X is%.2f\n", x);

Eg: the product of 123 and 456

printf ("Result:%d \ n", 123*456);

Or

int a = 123;

printf ("Result:%d \ n", a*456);

Summary:

1, learn the use of printf, note that the parameters are separated by commas in half-width

2. Use%d to print integers, use%04d to control width

3,%f to print decimals, using%.4f to control the number of digits after the decimal point

4, learn to define the int type variable, represent the integer

5, learn to define a double type variable, representing decimals

6, preliminary study simple +-*/the expression

2.3 scanf

Scan Scanning F format

Used to receive user input from the console

Enter an integer:

int n;

scanf ("%d", &n);

Enter decimal

Double X;

scanf ("%lf", &x); Lf--long float

Wait for user input

Input: 123

RESRLT:

int n;

printf ("Please input:"

scanf ("%d", &n);

printf ("Result:%d \ nthe", N)

scanf: One-time input multiple number

int A;

Double X;

printf ("Please input");

scanf ("%d,%lf", &a, &x);

printf ("Result:%D,%LF \ n", a,x)

scanf ("%d,%lf", &a, &x);

scanf ("%d-%lf", &a, &x);

scanf ("%d*%lf", &a, &x);

Note: Enter the time strictly according to the format to

To compare a complex format:

scanf ("AAA%DBBB%LFCCC", &a, &x);

Eg:1\ lets the user enter the month and year date in the format "2015-3-23".

Extract the year, month, day, replace as "2015/3/23" slash format output

int year;

int manth;

int day;

scanf ("%d-%d-%d", &year,&month,&day);

printf (%d/%d/%d ", year,month,day);

Eg2\ implements a program that calculates the product of any two decimals, prompting the user to first enter 2 numbers in the console and then print the product

To use this program for others

Double X;

Double y;

printf ("Please input:");

scanf ("%lf,%lf", &x, &y);

printf ("Result:%.3LF \ n", x*y);

Summary:

scanf How to enter data:

1. Define variables first, integers using int, decimal with double XI type

2. Using%d or%LF

3. Note the use of the & number before the parameter

Note printf scanf